P0513 on 2018 Fiat 500X: Invalid Key & No-Start Fixes

What's Unique About the 2018-2018 Fiat 500X

For Fiat-Chrysler vehicles like the 500X and its platform-mate, the Jeep Renegade, the P0513 code is closely tied to its specific Sentry Key Immobilizer (SKIM) or Wireless Control Module (WCM) system. A notable issue, confirmed by manufacturer Technical Service Bulletin (TSB) #S2208000073, is that this code can appear after a software update or replacement of the main computer (PCM). This indicates a higher-than-usual sensitivity to programming and module synchronization on this platform. Low voltage from a dying vehicle battery is also a known trigger for corrupting the security data in the PCM, leading to this code.

Diagnostic Flowchart

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

Symptoms You May Notice

• Engine cranks but will not start
• Engine starts and then immediately stalls
• Vehicle will not start at all
• Flashing red security light on the dashboard
• "Invalid Key" or similar message may appear on the instrument cluster
• Keyless entry remote may still lock and unlock the doors even if the car won't start

Most Likely Causes

1. Dead or Weak Key Fob Battery 🔴 High Probability Key fob batteries have a finite life and are a common failure point for any vehicle with a keyless ignition or transponder key system.
   How to confirm: Try using the spare key. If the spare key works, the issue is with the primary key or its battery. You can also try the emergency start procedure: press the start/stop button with the nose of the dead key fob instead of your finger. If the car starts, the fob battery is dead.
   Typical fix: Replace the CR2032 battery inside the key fob. 🎬 Watch: How to replace your Fiat 500X key fob battery
   Est. part cost: $1-$5
2. PCM/WCM Programming Issue or Data Corruption 🟡 Medium Probability A specific TSB (#S2208000073) exists for this model, indicating that a P0513 code can be set after the PCM is reprogrammed (flashed) or replaced. Low voltage from a weak or dead vehicle battery is also known to corrupt the EEPROM data in the PCM, causing it to lose synchronization with the other security modules.
   How to confirm: This is typically diagnosed by a dealer after confirming the keys are good. If the issue appeared immediately after a software update, module replacement, or a dead vehicle battery, this is the most likely cause.
   Typical fix: The dealer must perform a specific 'PCM Replaced' routine and/or a 'Proxy Configuration Alignment' to resynchronize the modules as outlined in TSB S2208000073. In severe corruption cases, the PCM may need to be removed and its EEPROM data re-flashed on the bench.
   Est. part cost: $0 (if related to recent service) - $250 (for programming)
3. Faulty Key Fob 🟡 Medium Probability The internal transponder chip in the key can be damaged from being dropped or from water exposure.
   How to confirm: If replacing the battery does not work, the emergency start procedure fails, and the spare key starts the car, the original key is faulty.
   Typical fix: The key fob must be replaced and programmed to the vehicle by a dealer or a qualified automotive locksmith.
   Est. part cost: $150-$400
4. Faulty Wireless Control Module (WCM) / RF Hub ⚪ Low Probability This module acts as the receiver for the key's signal and can fail electronically, though it's less common than key or programming issues.
   How to confirm: A professional scan tool is needed to check for communication with the WCM/RF Hub. If the module is unresponsive or fails self-tests, and its wiring is intact, it is likely faulty.
   Typical fix: Replace the WCM/RF Hub module and program it to the vehicle, along with all keys. This requires dealer-level tools.
   Est. part cost: $100-$300

Rare But Worth Checking

• Faulty Ignition Switch or Antenna Ring: The antenna ring around the ignition switch (or start button) picks up the key's signal. If it fails, the signal is never sent to the security module. This is less common than key or module failures but worth checking.
• Wiring Harness Issue: A damaged wire or poor connection between the WCM, PCM, and ignition antenna can cause an intermittent or total loss of communication, triggering the P0513 code.

Diagnosis Steps

1. Try the spare key. If it works, the problem is with the primary key fob.
2. If the spare key also fails, try the emergency start procedure: press the start/stop button directly with the nose of the key fob. If the car starts, the fob battery is dead.
3. If the emergency start fails, replace the CR2032 battery in one of the key fobs as a low-cost next step.
4. Check the dashboard for a flashing red security light, which confirms an active immobilizer issue.
5. If keys are not the issue, the vehicle must be scanned with a professional-grade tool (like wiTECH or AlfaOBD) that can access the immobilizer/WCM data stream. Check for related codes like B1A25 or B1A28.
6. Confirm communication with the WCM/RF Hub, BCM, and PCM. Check for any other related trouble codes.
7. If the issue occurred after a recent service, battery replacement, or jump-start, reference TSB S2208000073. The dealer must perform the 'Proxy Configuration Alignment' and/or 'PCM Replaced' routine.
8. If there is no communication with the WCM/RF Hub, inspect its wiring and connectors for damage before condemning the module. Pay special attention to the main chassis and gearbox ground straps for corrosion.
9. If the WCM is faulty, it will need to be replaced and programmed by a dealer or specialist.

Parts You'll Likely Need

• Key Fob Battery (OEM #CR2032) — This is the most common and cheapest potential fix for a key that is no longer transmitting its signal.
  Trusted brands: Energizer, Duracell, Panasonic
  OEM price range: $5-$10
  Aftermarket price range: $1-$5
• Key Fob / Transponder Key (OEM #68204562AC (replaces 68204562AA, 68204562AB)) — If the internal transponder chip fails or the fob is damaged, the entire key fob must be replaced and programmed to the vehicle.
  Trusted brands: Mopar (OEM)
  OEM price range: $120-$180
  Aftermarket price range: $50-$100
• Wireless Control Module (WCM) / RF Hub — This module is the brain of the security system. It can fail internally, requiring replacement and programming.
  Trusted brands: Mopar (OEM)
  OEM price range: $150-$300
  Aftermarket price range: $100-$200

Technical Service Bulletins (TSBs) & Recalls

• S2208000073: No Start, After Flash And Or PCM Replace, DTC P0513 Invalid Skim Key Setting.

Platform-Specific Known Issues

• TSB S2208000073 addresses a no-start condition with DTC P0513 specifically after the Powertrain Control Module (PCM) has been reprogrammed (flashed) or replaced. The official fix is to run the 'PCM Replaced' routine and a 'Proxy Configuration Alignment' using a dealer scan tool to re-establish the security handshake between the PCM, BCM, and RF Hub.
• Low voltage events from a dying or disconnected main vehicle battery are a very common trigger for this code on the 500X and its platform-mate, the Jeep Renegade. The voltage drop can corrupt the security key data stored in the PCM's EEPROM, causing a mismatch even when the keys are perfectly fine.

Mechanic-Grade Diagnostic Values

• Immobilizer Antenna Ring Resistance — expected: A specific Ohm value is not published, but the circuit should show continuity and not be an open circuit.. Failure: An open circuit (infinite resistance) or a short to ground indicates a failed antenna ring.

Hidden / Shadow Codes Worth Checking

• B1A25: Invalid Key - This code is stored in the RF Hub/WCM and indicates that the key read by the antenna is not one of the keys programmed into the vehicle's memory. (see via A professional scan tool with FCA-specific capabilities, such as wiTECH or AlfaOBD, is required to read codes from the RF Hub.)
• B1A28: ECM Mismatch with SKIM / VIN Mismatch - This code indicates a disagreement between the security information (like the VIN) stored in the Powertrain Control Module (PCM) and the security module (RF Hub/BCM). This is common after module replacement or data corruption. (see via Requires an advanced scan tool (wiTECH, AlfaOBD) capable of reading Body Control Module and security system fault codes.)

Scan Tool Commands That Help

• wiTECH or AlfaOBD: Proxy Configuration Alignment — This procedure is used to synchronize the configuration of all electronic modules on the CAN network. It must be run anytime a module is replaced, added, or removed to prevent communication errors and a flashing odometer. It is often required to clear security faults after fixing the root cause.
• wiTECH: PCM Replaced — This specific routine, found in the BCM menu, MUST be run *before* a Proxy Alignment when a new or flashed PCM is installed. It initializes the security handshake between the new PCM and the rest of the vehicle as noted in TSB S2208000073.
• AlfaOBD: Read PIN — This function, found under the RF Hub module menu, can extract the vehicle's 4-digit security PIN code. This PIN is required to perform key programming procedures and other security-related functions.

Wiring & Ground Locations

• Body Control Module (BCM) — The BCM is integrated with the interior fuse box, located on the driver's side of the vehicle, behind the lower dashboard panel, to the left of the steering column.. The BCM is a central node in the immobilizer system. All security communications between the key, RF Hub, and PCM pass through it. A poor connection or internal fault in the BCM can directly cause a P0513 code.
• Main Earth/Ground Strap — A primary ground strap connects the battery negative terminal/chassis leg to the gearbox/engine block. It is located underneath the battery and battery tray.. Corrosion or failure of this main ground can cause unstable voltage and electrical noise throughout the vehicle. This can lead to unpredictable behavior in sensitive modules like the PCM and BCM, potentially causing data corruption that triggers a P0513 code.

Real Owner Repair Stories

• MHH AUTO Forum (2017 Jeep Renegade (shared platform)) — No start condition with DTC P0513 present in the PCM after the main vehicle battery went dead.
  ❌ Tried (didn't work) Proxy Alignment procedure completed successfully but did not fix the issue., Attempting to reprogram the existing keys failed.
  ✅ What actually fixed it The PCM's internal EEPROM memory was corrupted by the low voltage event. The fix required removing the PCM from the vehicle, reading the corrupted data with a bench-top tool (like KTAG), flashing a 'virgin' (blank) software file to it, and then reinstalling it and performing a full initialization and key programming procedure with a dealer tool.
• Reddit r/MechanicAdvice (2009 Jeep Liberty) — P0513 code appeared, engine would click but not crank or start. Remote start also stopped working.
  ❌ Tried (didn't work) Resetting the key by leaving it in the 'ON' position.
  ✅ What actually fixed it The issue, despite the immobilizer code, was simply a dead main vehicle battery. Replacing the battery resolved the no-start condition and the code.

When the Usual Fixes Don't Work

• While the TSB and common knowledge point to a 'Proxy Configuration Alignment' as the fix for synchronization issues, there are documented cases where this is not sufficient. On the identical Jeep Renegade platform, a P0513 code caused by a dead battery required a full bench re-flash of the PCM's EEPROM with a 'virgin' file. The standard Proxy Alignment and key programming routines repeatedly failed because the underlying security data in the PCM was too corrupted for the scan tool to repair. This indicates that in severe cases of data corruption, module-level software repair is necessary, which is beyond the capability of dealer-level scan tools.

OEM Part Supersession History

• 68291647AJ, 68291647AK, 68434597AB, 68434597AC, 68434597AD, 68434597AE, 68525461AA, 68525461AB → 68583952AA — Part has been updated by the manufacturer over time.
  Heads up: These part numbers are for the Wireless Control Module / RF Hub. While listed as compatible, always verify the correct part number for your specific vehicle's VIN before ordering, as programming is required.