OBD-II Code B1600: Ignition Key Communication Error

What Does B1600 Mean?

B1600 means your car's computer, specifically the Passive Anti-Theft System (PATS), cannot detect a signal from the security transponder chip embedded in your ignition key. The system requires this electronic handshake to verify the key is legitimate before enabling the engine. When it receives no signal, it assumes a theft attempt, logs the B1600 code, and immobilizes the engine by disabling the fuel injectors and starter.

Technical definition: The official SAE/ISO definition for this code, primarily used by Ford, is "PATS Ignition Key Transponder Signal Is Not Received". This indicates the control module (Instrument Cluster or PCM) received no signal from the ignition key's transponder via the transceiver antenna during the startup sequence.

Can I Drive With B1600?

No — Do Not Drive. The vehicle is immobilized by design. It either cranks without starting or starts and immediately stalls within two seconds. Driving is impossible until the anti-theft system fault is repaired.

Common Causes

• Damaged or Defective Key Transponder (Very Common) — The electronic chip inside the key's plastic head is the most common failure point. Dropping the key, water exposure, or age damages the chip, preventing it from transmitting its security code.
• Faulty PATS Transceiver (Common) — The transceiver is an antenna ring around the ignition lock cylinder that powers the key's chip and reads its signal. Heat cycles and vibration cause internal circuit failures, breaking communication with the key.
• Use of a Non-Programmed or Poorly Cloned Key (Common) — Using a new key that lacks professional programming, or a low-quality hardware store copy, triggers this code. The vehicle's computer rejects the unrecognized signal.
• Signal Interference on Keychain (Common) — Large metal objects, other transponder keys, or RFID fobs (like gas station payment tags) on the same keychain block the low-frequency signal between the key and the transceiver ring.
• Corroded Fuel Pump Driver Module (FPDM) (Less Common) — On 2004-2008 Ford F-150s and Expeditions, a corroded FPDM blows the fuel pump fuse and causes a crank-no-start. The ECU frequently misinterprets this fuel system failure and logs a false B1600 code.
• Aftermarket Remote Starter/Alarm Malfunction (Less Common) — Poorly installed aftermarket remote starts interfere with the factory anti-theft signal. A failing bypass module prevents the PATS transceiver from reading the physical key.
• Wiring or Connector Issue (Less Common) — A loose connector, broken wire, or corroded pin between the transceiver antenna and the Powertrain Control Module (PCM) interrupts the signal path.
• Low Vehicle Battery Voltage (Rare) — Extremely low system voltage during engine cranking causes unpredictable communication drops between the PATS module and the PCM.
• Faulty Control Module (PCM/IC) (Rare) — A complete failure of the Powertrain Control Module or Instrument Cluster is rare. Only consider this after definitively ruling out the key, transceiver, and wiring.

Symptoms

• Engine Will Not Start (Crank-No-Start) — The starter turns the engine over, but the computer prevents it from firing because the fuel system is disabled.
• Rapidly Flashing Anti-Theft Light — When turning the key to 'ON', the security or 'THEFT' light on the dashboard flashes rapidly instead of turning on solid for three seconds.
• Engine Starts and Immediately Stalls — On some vehicle models, the engine fires and runs for approximately two seconds before the anti-theft system abruptly shuts it down.
• Instrument Cluster Gauges Inoperative (Some Models) — On 2004-2011 Ford Rangers, a PATS fault causes the speedometer, tachometer, and temperature gauges to fail, with the odometer displaying only dashes.
• Stored Body Trouble Code (scan-tool only — no driver-felt sign) — The B1600 code is stored in the vehicle's memory, requiring an OBD-II scanner capable of reading Body ('B') codes.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this code.

Common Fixes & Costs

• Cut and Program a New Transponder Key — Parts: $20-$50 for the key blank., Labor: $120-$250 for cutting and programming by an automotive locksmith. Dealer pricing is $200-$400+., ~0.8 hr book time (Professional)
• Replace PATS Transceiver Antenna Ring — Parts: $40-$100, Labor: $120-$180, as it's typically a one-hour job., ~1 hr book time (Intermediate)
• Replace Fuel Pump Driver Module (FPDM) — Parts: $50-$100 for an aftermarket or OEM part., Labor: $60-$150. This is a specific fix for certain Ford models where the FPDM is the true cause of the no-start., ~0.7 hr book time (Intermediate)
• Reprogram Existing Keys — Parts: $0, Labor: $120-$250. This is necessary if the vehicle's security memory was lost or corrupted., ~1 hr book time (Professional)
• Repair Damaged Wiring — Parts: $10-$30 for connectors and wire., Labor: $150-$450+, highly variable depending on the location and extent of the damage., ~3.5 hr book time (Professional)

Used vs. New Parts: Buying Guide

When a used part is worth it: For mechanical, non-wear parts like the PATS transceiver or a Fuel Pump Driver Module (FPDM), a used part from a reputable salvage yard is a cost-effective option.

Donor-vehicle mileage cap: roughly under 120000 miles for the part to have meaningful remaining life.

Donor quality checklist:

• For FPDMs, visually inspect the aluminum housing for corrosion or cracks before buying.
• For transceivers, ensure the wiring and connector are intact with no signs of damage.
• Match the part number exactly. Superseded part numbers are often incompatible.

Decision logic:

• If The part is a transponder key. → Must buy new. Used keys from other vehicles cannot be reprogrammed to your car.
• If The part is a PATS transceiver and the new cost is under $100. → Buy new for peace of mind and warranty. The labor to replace a failed used part negates the savings.
• If The part is an FPDM for a Ford truck. → Buy a new aftermarket 'OE FIX' version, which includes design improvements like standoffs to prevent future corrosion.

Warranty tradeoff: Used parts typically offer a 30-90 day warranty. New aftermarket parts offer 1 year to a limited lifetime warranty. New OEM parts offer a 1-2 year warranty.

Worst-case if a used part fails: $200-$400 if a used electronic part fails after the warranty period, requiring repeat labor and a new part.

What Happens If You Wait — Timeline

1. First Occurrence (Intermittent): The vehicle fails to start once, with a rapidly flashing theft light. It starts on subsequent attempts. Extreme cold or heat often triggers this. (MPG impact: 0%% · Added cost: $0)
2. 1-4 Weeks (Frequent Intermittent): The no-start condition happens several times a week. The driver must cycle the key multiple times or reposition it to get a successful read. (MPG impact: 0%% · Added cost: $0)
3. 1-2 Months (Hard Failure): The faulty component fails completely. The vehicle is permanently immobilized and fully stranded. (MPG impact: N/A% · Added cost: $100-$150 for a tow to a repair shop or locksmith.)
4. 2+ Months (Compounded Failure): Repeated crank-no-start attempts drain and permanently damage the battery, compounding the initial PATS fault with a dead battery. (MPG impact: N/A% · Added cost: $250-$470 (towing cost plus $150-$320 for a new battery).)

Cost of Not Fixing It

• Immediate: The vehicle is completely immobilized and will not start, resulting in being stranded. (Added cost: $100-$250 for a tow to a repair shop or dealership.)
• 1-7 Days: Repeated failed start attempts drain the vehicle's battery, requiring a jump start or a new battery. (Added cost: $150-$250 for a replacement battery.)
• Long-Term: There is no progressive mechanical damage from ignoring a B1600 code, as the vehicle cannot be operated. The primary cost is the loss of use of the vehicle.

Diagnosis Steps

1. Try a Different Programmed Key
   Insert a known-good spare key. If the engine starts normally, the original key's transponder chip is dead and requires replacement.
   Tools: Spare programmed key (Beginner)
2. Simplify the Keychain
   Remove all other keys, RFID fobs, and large metal objects from the keychain. Attempt to start the vehicle with only the single ignition key to eliminate signal interference.
   Tools: None (Beginner)
3. Interpret Anti-Theft Light Flash Codes
   Turn the key to 'ON' and watch the flashing 'THEFT' light. After rapid blinking, it pauses and flashes a two-digit code. Code 13 (one flash, pause, three flashes) confirms a missing key signal.
   Tools: None (Intermediate)
4. Inspect the Fuel Pump Driver Module (FPDM) on Ford Trucks/SUVs
   If diagnosing a 2004-2008 Ford truck, locate the FPDM on the frame rail above the spare tire. If the aluminum housing is corroded or cracked, replace it immediately, as this falsely triggers PATS codes.
   Tools: 8mm and 10mm sockets, ratchet (Intermediate)
5. Inspect Transceiver and Wiring
   Remove the plastic steering column shrouds. Visually inspect the transceiver ring around the ignition cylinder for cracks, and ensure its 4-pin electrical connector is securely seated.
   Tools: Screwdrivers, trim removal tools (Intermediate)
6. Check Vehicle Battery and Fuses
   Test the battery to ensure it holds at least 12.4 volts. Check the interior fuse panel for blown fuses related to the PATS, instrument cluster, or PCM.
   Tools: Multimeter (Beginner)
7. Scan for All Related Codes
   Use a scanner capable of reading Body (B) codes. Check for B1681 or B2103, which definitively point to a failed transceiver rather than a bad key.
   Tools: Advanced OBD-II Scan Tool (Intermediate)
8. [PRO TIP] Analyze Live Data PIDs
   Monitor the 'PATS_KEY_STATUS' PID. The status must change to 'VALID' when turning a good key to the ON position. A 'NOT_FOUND' status confirms a communication break.
   Tools: Advanced OBD-II Scan Tool (e.g., FORScan) (Advanced)
9. [PRO TIP] Perform Transceiver Voltage and Resistance Test
   Disconnect the transceiver. The ground wire must read under 5 ohms to chassis ground. With the key ON, the power wire must show over 10 volts.
   Tools: Multimeter, vehicle-specific wiring diagram (Advanced)
10. [PRO TIP] Check Fuel Pressure (Ford Trucks/SUVs)
    Connect a gauge to the fuel rail. Zero pressure during cranking on a Ford truck strongly suggests a blown fuel pump fuse or dead FPDM, rather than a true PATS failure.
    Tools: Fuel pressure gauge (Advanced)
11. [PRO TIP] Check Transceiver Signal with Oscilloscope
    Connect an oscilloscope to the transceiver's TX/RX wires. A complete lack of an RF burst waveform when turning the key ON confirms a dead transceiver.
    Tools: Oscilloscope, wiring diagram (Advanced)

When This Code Triggers (Freeze-Frame Conditions)

• Event Trigger: Key ON or Crank (The B1600 code sets during the vehicle start sequence when the ignition turns to the 'ON' or 'START' position.)
• Vehicle Speed: 0 MPH (The vehicle is stationary when the Passive Anti-Theft System (PATS) performs its key-read sequence.)
• Engine RPM: 0 or Cranking RPM (e.g., <300) (The engine is off or being cranked by the starter when the control module fails to receive the key's transponder signal.)
• Battery Voltage: 10.5V - 12.6V (The code sets under normal battery voltage conditions, though exceptionally low voltage during cranking exacerbates communication errors.)

Related Codes

• B1601 — This code means the system received a valid signal format, but the key's ID code was not on the vehicle's 'approved' list. B1600 means the system sees nothing; B1601 means the system successfully reads a key, but rejects it.
• B1602 — Indicates a partial or corrupted signal was received from the key. B1600 is a total lack of signal; B1602 means a signal was detected but garbled. This points to signal interference from the keychain.
• P1260 — A powertrain code meaning 'THEFT DETECTED, VEHICLE IMMOBILIZED'. This code is the effect, while B1600 is the cause. The PATS module sets B1600, then tells the PCM to immobilize the engine, setting P1260.
• B1681 — Means 'PATS Transceiver Module Signal Is Not Received'. B1600 means the transceiver didn't get a signal from the key; B1681 means the control module didn't get a signal from the transceiver.
• B2103 — Means 'Transceiver Antenna Not Connected'. This is a more specific code than B1681, pointing directly to a damaged or disconnected transceiver ring.

Climate & Environmental Factors

• Extreme Cold: Causes intermittent B1600 codes. Cold weather causes hairline cracks in solder joints on the transceiver's circuit board to contract and lose connection.
• Extreme Heat: High interior cabin temperatures (over 130°F / 54°C) cause PATS components to fail. The components work again once they cool down, indicating a thermal-related circuit failure.
• High Humidity / Rain: Moisture ingress into wiring harnesses or connectors causes shorts or corrosion, leading to intermittent signal loss. This is common in vehicles with known windshield or firewall water leaks.
• Road Salt (Rust Belt Regions): The primary cause of Fuel Pump Driver Module (FPDM) failure on Ford trucks. Salt spray corrodes the aluminum housing, compromising the internal electronics and causing a no-start that mimics a PATS problem.

Where to Take It: Dealer vs Independent vs Chain

• Dealer: Use as a last resort. A locksmith is almost always a better first call for a key or programming issue.
  Best for: Vehicles still under warranty., Complex cases involving replacement of a PCM or Instrument Cluster requiring a 'Parameter Reset'.
  Downsides: Highest labor rates and part costs., More likely to replace entire components rather than diagnose simple wiring issues. (Typical cost: +50% vs. baseline)
• Independent Shop: A good choice, but call first to confirm they handle Ford PATS diagnostics. If the problem is just the key, a locksmith is more direct.
  Best for: Diagnosing and replacing the PATS transceiver or tracing a wiring fault., Investigating related issues like a faulty FPDM on Ford trucks.
  Downsides: May lack the specialized equipment to program new keys if all keys are lost., Quality varies; ensure they have experience with anti-theft systems. (Typical cost: +0% vs. baseline)
• Chain Shop: AVOID. They are not equipped to properly diagnose or repair a B1600 code.
  Best for: Battery testing and replacement.
  Downsides: Technicians lack the specialized training and tools for anti-theft system diagnostics and key programming., High risk of misdiagnosis. (Typical cost: -10% vs. baseline)

When to Walk Away From the Repair

If the estimated repair cost for the B1600 fault exceeds 50% of your car's private-party value, consider your options. Since this repair is often under $300, it rarely triggers this threshold on its own.

• Car worth $3000, fix is $250: Fix it. The repair cost is a small fraction of the vehicle's value and makes it operational again.
• Car worth $1500, fix is $800: Walk away. If the diagnosis points to a rare, expensive failure like the instrument cluster or PCM, the repair cost exceeds the car's worth.
• Car worth $8000, fix is $250: Fix it without question. This is a minor cost to keep a valuable asset running.

What Scan Tool You Need for This Code

Minimum: A scanner that reads manufacturer-specific Body ('B') codes. A basic engine code reader that only shows 'P' codes will NOT see a B1600.

A $20 code reader shows 'No Codes Found' because it cannot access the body control module where PATS faults are stored.

Budget: BlueDriver Pro (~$100) — Connects to your smartphone and reads/clears Body codes like B1600, providing freeze-frame and live data to rule out basic issues.

Mid-range: FORScan software with OBDLink EX adapter (~$120) — The best DIY option for Ford owners. FORScan with an extended license performs advanced functions like PATS key programming, erasing all keys, and adding new ones, saving hundreds of dollars at a locksmith.

Professional: Autel MaxiIM IM508S / XTOOL D7 (~$500-800) — Professional-grade tools combining full-system diagnostics with advanced immobilizer and key programming functions. They perform parameter resets and program keys for nearly all brands.

Rent vs buy: You cannot rent the specialized tools (FORScan, Autel IM) needed for key programming. For any actual repair involving programming, you must buy the appropriate tool or hire a professional.

How to Clear the Code After You Fix It

1. Reconnect any disconnected components (e.g., battery, transceiver).
2. Use a compatible OBD-II scan tool to command 'Clear DTCs'. A simple battery disconnect does not clear body codes.
3. Cycle the ignition from OFF to ON with a valid, programmed key. Observe the anti-theft light; it must illuminate for 3 seconds and then go out to confirm a successful key read.
4. Start the vehicle to confirm the repair is complete.

Drive cycle (~5 minutes): A formal drive cycle is not required. The system self-tests every time the ignition turns on. After clearing the code, successfully starting the engine confirms the fix.

Readiness monitors affected: None directly. However, disconnecting the battery to perform the repair resets all emissions readiness monitors.

Before emissions retest: drive at least 50 miles to fully set monitors.

Watch out for:

• Using a basic code reader that cannot access Body ('B') codes fails to clear the B1600.
• Clearing the code without fixing the root cause results in the code returning immediately on the next key cycle.
• Forgetting that a battery disconnect resets all modules, requiring radio codes or window initializations.

Will This Fail Emissions / State Inspection?

Yes — this code typically fails an OBD-II emissions inspection.

• California: Will fail. An illuminated anti-theft light is a cause for failure. If B1600 is accompanied by P1260, the Check Engine Light illuminates, causing an automatic OBD-II failure.
• New York: Will fail. The NYS inspection includes a check of all warning lamps. An illuminated security light results in a safety inspection failure.
• Texas: Will fail. Any illuminated malfunction indicator lamp (including a dedicated security light related to engine controls) causes the vehicle to be rejected from testing.

Most Commonly Affected Vehicles

• Ford F-150 (1998-2014) — Extremely common. Models from 2004-2008 are highly susceptible to Fuel Pump Driver Module (FPDM) failure, which mimics a PATS issue and logs a B1600 code.
• Ford Ranger (1998-2011) — Very common. On 2004-2011 models, the PATS function is integrated into the Hybrid Electronic Cluster (HEC). A cluster failure causes B1600 along with gauge malfunctions.
• Ford Mustang (1996-2014) — One of the first models with PATS. For 1996-1998 models, Ford issued service information about overlaying the transceiver wiring harness to fix intermittent issues.
• Ford Explorer (1998-2010) — A very common fault code reported by owners, typically solved with a new key or transceiver.
• Ford Expedition (1997-2014) — Shares the PATS architecture with the F-150. The 1997-1998 models had a TSB regarding wiring harness overlays for intermittent faults.
• Mazda B-Series (B2300, B3000, B4000) (1998-2009) — These trucks are badge-engineered versions of the Ford Ranger and use the identical Ford PATS system, making them prone to the exact same B1600 faults.
• Jaguar S-Type, X-Type (2000-2008) — During Ford's ownership, these models used a PATS-based immobilizer system. B1600 appears for key communication failures, though key programming is more specialized.
• Lincoln LS, Navigator, Town Car (1998-2011) — As Ford's luxury brand, these vehicles use the same PATS architecture. The Lincoln Aviator also reports this code causing intermittent stalling.

Manufacturer-Specific Notes

• Ford / Lincoln / Mercury / Mazda (Ford-based): This code is a hallmark of the Passive Anti-Theft System (PATS). The 'theft' light on the dash flashes a diagnostic code after its initial rapid blinking. Code 1-3 means 'unprogrammed key', while 1-1 means 'transceiver not connected'.
• Ford: For 2004-2008 trucks/SUVs, Ford issued Customer Satisfaction Program 07M07, extending the warranty on the Fuel Pump Driver Module (FPDM) due to corrosion. For 2009-2014 F-150s, TSB 15-0137 addresses a melting fuel pump fuse (#27) that mimics FPDM failure.
• General Motors (Chevrolet, GMC, etc.): GM uses code B1600 for a completely different problem: 'Left Front Mirror Motor Circuit Malfunction'. If you have a GM vehicle, this code is entirely unrelated to the anti-theft system.
• Acura / Honda: On some older models, B1600 indicates a 'Communication Bus Line Error', pointing to a general network problem. It is not a standard code for their immobilizer systems.
• Hyundai / Kia: The string 'B1600' is not used as a diagnostic trouble code. It appears in part numbers, such as 97216-B1600 (an actuator) or 95400-B1600 (a body control module).
• Saab: On some Saab models like the 9-3, code B1600 indicates a malfunction with the Saab Information Display (SID) or a related bus communication error, and is not related to the immobilizer key.
• Jaguar: While using a Ford-based PATS system during the Ford ownership era, Jaguar key programming is more complex. Not all automotive locksmiths have the software to program Jaguar keys, necessitating a European car specialist.

Real Owner Stories

2005 Ford Ranger with intermittent no-start

Weeks after getting two new keys from a locksmith, the truck began intermittently failing to start, flashing the 'THEFT' light.

What they tried:

1. Replaced the PATS transceiver, but the problem persisted.
2. Read the theft light flash code, which was 13 (correlating to B1600).
3. Tried the second new key made by the locksmith.

Outcome: The truck started immediately with the second key. The first new key had a faulty transponder chip. The owner used the second key without issue, proving the transceiver replacement was unnecessary.

Lesson: Always try your spare key first. A faulty transponder chip inside the key is the most common cause of a B1600 code.

2006 Ford F-150 crank-no-start misdiagnosed as PATS

The truck cranked but would not start, storing a B1600 code. The owner suspected a complex anti-theft system failure.

What they tried:

1. Researched the B1600 code and found forum posts about the Fuel Pump Driver Module (FPDM) on 2004-2008 F-150s.
2. Inspected the FPDM located on a frame cross-member above the spare tire.

Outcome: The FPDM's aluminum housing was severely corroded and cracked open. Replacing the $70 FPDM and clearing the codes permanently resolved the no-start. The B1600 was a false code triggered by the fuel system failure.

Lesson: On 2004-2008 Ford trucks, a no-start with a B1600 code is often misleading. Always inspect the FPDM for corrosion before spending money on keys or PATS diagnostics.

2001 Ford Mustang with B1600 after PCM replacement

The owner replaced the Powertrain Control Module (PCM) for an unrelated issue, but the car refused to start afterward, displaying a flashing theft light and code B1600.

What they tried:

1. Attempted to clear codes with a standard OBD-II scanner.
2. Hired a locksmith to erase and reprogram the keys.

Outcome: The PATS module (in the instrument cluster) and the new PCM lacked an electronic handshake. A 'Parameter Reset' using FORScan software was required to synchronize the modules. Once performed, the existing keys were recognized and the car started.

Lesson: When replacing a major control module like the PCM or instrument cluster, a simple key reprogram is insufficient. A 'Parameter Reset' is mandatory to synchronize the security system.

How to Prevent This Code From Triggering

• Protect Your Transponder Key (Daily Habit) — Avoid dropping keys on hard surfaces or exposing them to moisture. Physical damage to the key's plastic head is the primary cause of chip failure.
• Isolate Your Ignition Key (Every time you drive) — Remove multiple transponder keys or electronic fobs from the same keychain. Competing radio signals interfere with the transceiver, causing B1600 or B1602 codes.
• Inspect and Protect the FPDM (Ford Trucks) (Once every 2-3 years (especially in the Rust Belt)) — The aluminum Fuel Pump Driver Module on Ford trucks suffers severe galvanic corrosion when mounted directly to the steel frame. Remove it, clean the frame, and reinstall with standoffs to prevent moisture buildup.
• Store Keys in a Signal-Blocking Pouch (When at home or in public) — A Faraday pouch blocks all RF signals, preventing stray signals from corrupting the key's programming and protecting against relay theft attacks.
• Maintain a Healthy Battery (Every 3-5 years) — Low system voltage during cranking causes communication glitches between the PATS module and the PCM. Replace batteries older than 4 years to ensure stable voltage.

Frequently Asked Questions

What is the most common misdiagnosis for a B1600 code?

The most costly mistake is replacing the Powertrain Control Module (PCM) before testing simpler components. The fault almost always lies with the key, the transceiver antenna, or the wiring. Always test a spare key and inspect the transceiver before suspecting the computer.

My car cranks but won't start and has a B1600 code. The spare key didn't work. What's next?

If a known-good spare key fails, the transceiver ring around the ignition lock is the most likely culprit. Visually inspect its connector and wires for damage. If intact, use a multimeter to verify power and ground at the transceiver harness.

Do I have to go to the dealer to fix a B1600 code?

No. A certified mobile automotive locksmith is usually the best choice. They possess the same programming equipment as dealers, charge significantly less, and come to your location to avoid tow fees.

What is a PATS 'flash code' and how do I read it?

When a fault occurs, the 'THEFT' light flashes rapidly, pauses, and blinks a two-digit code. For example, code 13 (one flash, pause, three flashes) indicates a missing key signal. This built-in diagnostic tool helps pinpoint the failure without a scanner.

Why does my car only have this starting problem when it rains or is very cold?

Temperature and moisture sensitivity strongly suggests a failing electrical component or wiring harness. Cold weather causes cracked solder joints inside the transceiver to contract and lose contact. Moisture creates shorts in damaged wiring near the firewall.

Can a cheap cloned key from a hardware store cause code B1600?

Yes. Low-quality cloned keys often emit weak signals that fail intermittently, causing the vehicle's computer to reject them and trigger a B1600 code.

Will replacing the car battery fix a B1600 code?

Replacing the battery rarely fixes the root cause of a B1600 code. However, an extremely weak battery causes low voltage during cranking, leading to module communication errors. Test the battery, but focus diagnostics on the key and transceiver.

Can I bypass the PATS system to get my car started?

Bypassing the PATS system is highly complex and requires specialized software to rewrite the PCM logic. It is not a practical DIY fix and compromises vehicle security. Properly diagnosing and replacing the faulty key or transceiver is the only reliable solution.

Key Takeaways

• Code B1600 indicates the Passive Anti-Theft System (PATS) cannot detect your ignition key, immediately disabling the fuel injectors and preventing the engine from starting.
• A damaged transponder chip inside the key causes over 60% of B1600 codes; always test a known-good spare key before buying replacement parts.
• On 2004-2008 Ford F-150s, a corroded Fuel Pump Driver Module (FPDM) above the spare tire frequently blows the fuel pump fuse and falsely triggers a B1600 code.
• Hire a mobile automotive locksmith instead of a dealership to cut and program new keys, saving an average of $150 and avoiding a $100 tow bill.