OBD-II Code P0098: Intake Air Temperature Sensor 2 Circuit High

What Does P0098 Mean?

P0098 means the Engine Control Module (ECM) detects the Intake Air Temperature (IAT) Sensor 2 voltage signal is above the normal operating range (typically over 4.8V). The computer interprets this high voltage as an impossibly cold air temperature, defaulting to -40°F. IAT Sensor 2, located after the turbocharger and intercooler, helps the engine calculate the correct air-to-fuel mixture.

Technical definition: SAE/OBD-II defines P0098 as "Intake Air Temperature Sensor 2 Circuit High (Bank 1)". The Powertrain Control Module (PCM) detects the IAT Sensor 2 voltage signal exceeds the specified range (>4.8V) for over 2 seconds. A "Circuit High" fault almost always indicates an open circuit. Bank 1 refers to the cylinder bank containing cylinder #1.

Can I Drive With P0098?

Yes, But With Caution. You can drive short distances to a repair shop, but long trips risk catalytic converter damage. Ignoring the code reduces fuel economy by 10-15%. Driving hundreds of miles causes carbon buildup and premature catalytic converter failure, costing $945 to $2,500. Stop driving and tow the vehicle if the engine hesitates severely or stalls.

Common Causes

• Sensor Unplugged After Recent Repair (Very Common) — This code frequently appears immediately after replacing an air filter or intercooler hose because technicians forget to plug the IAT sensor 2 connector back in, creating an open circuit.
• Faulty Intake Air Temperature (IAT) Sensor 2 (Very Common) — An internal open circuit or broken thermistor inside the sensor sends a constant high signal to the computer, failing to regulate voltage based on temperature.
• Damaged Wiring or Connector (Common) — Frayed, corroded, or cut wires create an open circuit, resulting in a maximum voltage reading at the PCM.
• Short to Voltage in the Signal Circuit (Less Common) — Damaged insulation allows the sensor's signal wire to touch a power source wire, sending a continuous high voltage signal directly to the engine computer.
• Aftermarket Intake or Modifications (Less Common) — Incorrectly installed cold air intakes damage the sensor, stress the wiring harness, or alter the thermal environment enough to trigger abnormal readings.
• Faulty Powertrain Control Module (PCM) (Rare) — The engine computer fails to correctly interpret the sensor signal. Consider this only after exhaustively ruling out wiring and sensor failures.

Symptoms

• Check Engine Light is On — The light illuminates as soon as the computer detects the high voltage fault for the specified duration.
• Decreased Fuel Economy — Fuel consumption increases by 10-15% because the computer enriches the fuel mixture, falsely believing the incoming air is freezing cold.
• Reduced Engine Performance — The engine feels sluggish, hesitates during acceleration, or exhibits a "flat" spot due to an incorrect air-fuel mixture.
• Rough Idle or Stalling — The engine shakes, runs unevenly, or stalls at idle due to an unstable air-fuel ratio.
• Hard Starting — The engine struggles to start in cold weather because the computer provides the wrong fuel amount based on the faulty sensor reading.
• Abnormal Fuel Trim Readings (scan-tool only — no driver-felt sign) — Scan tools display highly positive or negative long-term or short-term fuel trim values as the PCM compensates for the faulty temperature reading.

Common Fixes & Costs

• Reconnect Unplugged Sensor — Parts: $0, Labor: $0-$75, ~0.5 hr book time (DIY)
• Replace Intake Air Temperature (IAT) Sensor 2 — Parts: $20-$75, Labor: $50-$150, ~0.8 hr book time (DIY)
• Repair or Replace Damaged Wiring/Connector — Parts: $10-$40, Labor: $100-$350, ~2.5 hr book time (Intermediate)
• Replace Powertrain Control Module (PCM) — Parts: $600-$1500, Labor: $150-$300, ~1.5 hr book time (Professional)

DIY vs Professional

• Reconnect Unplugged Sensor — Beginner:
  Tools: Flashlight, hands.
• Replace Intake Air Temperature (IAT) Sensor 2 — Beginner:
  Tools: Basic hand tools (socket set, screwdrivers), flashlight.
• Repair or Replace Damaged Wiring/Connector — Beginner:
  Tools: Multimeter, wire strippers, wire crimpers, heat shrink tubing, soldering iron, wiring diagrams.
• Replace Powertrain Control Module (PCM) — Beginner:
  Tools: Advanced scan tools for programming, socket set.

Used vs. New Parts: Buying Guide

When a used part is worth it: Buying a used IAT sensor rarely makes sense. It is an inexpensive electronic component with a finite lifespan. Small cost savings are not worth the risk of premature failure.

Donor-vehicle mileage cap: roughly under 20000 miles for the part to have meaningful remaining life.

Donor quality checklist:

• Choose a part from a very low-mileage vehicle wrecked for non-engine reasons.
• Ensure the part number matches exactly.
• Avoid parts with corrosion on the pins or physical damage.

Decision logic:

• If The cost of a new OEM or reputable aftermarket IAT sensor is under $100. → Always buy new. The reliability and warranty are worth the cost.
• If The part is integrated into a much more expensive assembly (like a throttle body or MAP sensor). → Consider a low-mileage used assembly, but new is strongly preferred.

Warranty tradeoff: Used parts have a 30-90 day warranty. New aftermarket parts carry a 1-year to limited lifetime warranty. A new OEM part provides the best guarantee of correct calibration.

Worst-case if a used part fails: $100-$250 if a used sensor fails after the warranty period, requiring repeat labor and a new part.

Cost of Not Fixing It

• 0-1 month: Reduced fuel economy by 10-15%, poor acceleration, and hard starting. Failed emissions test. (Added cost: $20-$60 in wasted fuel.)
• 1-6 months: Continued driving with a rich fuel mixture causes carbon buildup on spark plugs and O2 sensors, and begins to overheat the catalytic converter. (Added cost: $200-$500 for O2 sensor or spark plug replacement.)
• 6+ months: Catastrophic failure of the catalytic converter. The substrate melts or clogs, causing severe performance loss. (Added cost: $1200-$2800 for catalytic converter replacement.)

Diagnosis Steps

1. Scan for Codes & Review Freeze Frame Data
   Use an OBD-II scanner to confirm P0098 is active. Review freeze-frame data to identify engine conditions (speed, temperature, load) when the code triggered.
   Tools: OBD-II Scanner (Beginner)
2. Visually Inspect the Sensor and Wiring
   Locate IAT Sensor 2 near the intercooler outlet or intake manifold. Check for an unplugged connector, broken wires, or corroded pins.
   Tools: Flashlight (Beginner)
3. Check Live Data from the IAT Sensor
   View the live data stream for the 'IAT Sensor 2' PID. A P0098 code typically shows a reading stuck at -40°F (-40°C) or a constant signal voltage over 4.8V that does not change as the engine warms up.
   Tools: OBD-II Scanner with Live Data (Intermediate)
4. [PRO TIP] Jumper Wire Test
   Unplug the sensor and use a jumper wire or paperclip to connect the signal and ground terminals on the harness connector. If the scan tool's live data jumps to a high value (e.g., 250°F+), the wiring and PCM are good, and the sensor is faulty. If it remains at -40°F, there is an open in the wiring.
   Tools: Jumper Wire, OBD-II Scanner with Live Data (Intermediate)
5. [PRO TIP] Perform a 'Wiggle Test'
   While monitoring live data, wiggle the wiring harness and connector. If the temperature or voltage reading flickers, you have a loose connection or an intermittent break in the wiring.
   Tools: OBD-II Scanner with Live Data (Intermediate)
6. Test the Sensor's Circuit at the Connector
   Unplug the sensor. With the key on and engine off, use a multimeter to verify a 5-volt reference signal (4.5V to 5.0V) on one wire and a good ground (< 5 ohms to chassis ground) on the other. Missing voltage indicates a wiring issue to the PCM.
   Tools: Multimeter (Intermediate)
7. Test the Sensor's Resistance
   Measure resistance across the unplugged sensor's terminals using a multimeter set to Ohms (Ω). Compare to the repair manual. For a definitive test, measure resistance in an ice bath (~32°F) and hot water. If the reading is infinite (O.L.) or doesn't change smoothly with temperature, replace the sensor.
   Tools: Multimeter, Thermometer, Ice, Hot Water (Advanced)
8. Check for an Open or Short in the Wiring
   If the jumper test failed, check for continuity in the signal and ground wires between the sensor connector and the PCM connector. High resistance (O.L.) indicates a broken wire requiring repair.
   Tools: Multimeter (Advanced)

When This Code Triggers (Freeze-Frame Conditions)

• Fault Trigger: Key On or Engine Running (An open circuit fault like P0098 is detected immediately when the PCM powers the circuit.)
• Engine Coolant Temp: 35-210°F (Occurs at cold start or when fully warmed up.)
• RPM: 0-3000 RPM (The fault logs at idle, during steady cruising, or during acceleration.)
• Vehicle Speed: 0-65 mph (Triggers while stationary or during city/highway driving.)

Related Codes

• P0097 — The opposite code: 'Circuit Low'. P0098 (High) is an open circuit (~5V signal), while P0097 (Low) is a short to ground (~0V signal). Unplugging a sensor with a P0097 code should change it to P0098, confirming the wiring is good and the sensor is internally shorted.
• P0113 — An identical 'Circuit High' fault for IAT Sensor 1 (pre-throttle body). If P0098 and P0113 appear together, suspect a shared wiring problem (power or ground) or a faulty PCM.
• P007D — 'Charge Air Cooler Temperature Sensor Circuit High'. On many Ford and GM vehicles, IAT sensor 2 and the charge air cooler temp sensor are the exact same part. Causes and diagnostics are identical to P0098.
• P007C — The 'Circuit Low' counterpart to P007D. Seeing P007C and P0098 together indicates an intermittent wiring problem that is both shorting and opening.

Climate & Environmental Factors

• Cold Weather: Cold temperatures exacerbate starting difficulties because the ECM cannot calculate the necessary fuel enrichment. It also makes plastic wiring insulation brittle and prone to cracking.
• High Humidity / Road Salt: Moisture and road salt penetrate the electrical connector, corroding pins and terminals to create the open circuit that triggers P0098.
• Altitude: The IAT sensor calculates air density, which decreases at higher altitudes. A faulty reading at high altitude causes pronounced sluggishness and poor fuel economy.

How to Clear the Code After You Fix It

1. Use an OBD-II scan tool to erase the fault codes.
2. Perform a complete OBD-II drive cycle to allow readiness monitors to run.
3. Re-scan to confirm the P0098 code does not return.

Drive cycle (~30 minutes): A general drive cycle includes: 1) Cold start (engine off overnight). 2) Idle for 2-3 minutes. 3) Drive at mixed city speeds (20-40 mph) for 10-15 minutes. 4) Drive at a steady highway speed (55-60 mph) for 10-15 minutes. 5) Safely coast to a lower speed without heavy braking.

Readiness monitors affected: Comprehensive Component Monitor, Catalyst Monitor, O2 Sensor Monitor

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

Watch out for:

• Clearing the code resets all readiness monitors to 'incomplete'; you cannot pass an emissions test until they are 'ready'.
• The code returns immediately if the root electrical fault (e.g., broken wire) was not fixed.
• Disconnecting the battery clears the code but resets all readiness monitors and learned adaptations.

Will This Fail Emissions / State Inspection?

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

• California: An illuminated Check Engine Light is an automatic failure. After repair, a complete drive cycle must set all readiness monitors before a retest.
• New York: A vehicle automatically fails the OBD-II inspection if the Check Engine Light is on. Clearing the code right before the test results in a failure due to 'Not Ready' monitors.
• Texas: In the 17 counties requiring emissions testing, an active P0098 code with the MIL on results in an inspection failure.

Most Commonly Affected Vehicles

• Ford F-150 (EcoBoost), Focus, Transit Custom (2011-2024) — IAT sensor 2 is a common failure point on EcoBoost engines. On the Transit Custom, broken wires at the intercooler sensor connector are a known issue visible from under the vehicle.
• Volkswagen/Audi Golf, Passat, Jetta, A3, A4, Q5 (2008-2019) — The sensor, often located in the plastic charge pipe between the intercooler and throttle body, frequently fails on these turbocharged models.
• Chevrolet Silverado, Cruze, Malibu, Equinox (2014-2024) — Common on turbocharged models. Distinguish IAT1 (often in the MAF) from IAT2 (post-intercooler) before replacing parts.
• BMW 1, 3, 5 Series, X1, X3, X5 (2007-2017) — Common on N54 and N55 engines, pointing to a failed sensor in the charge pipe just before the throttle body.
• Subaru WRX (2015-2021) — The post-intercooler IAT sensor 2 in the intake manifold on the FA20DIT engine is a known failure point with tight access.
• Honda Accord, Civic (especially Si, Type R) (2016-2024) — Common on 1.5L and 2.0L turbocharged engines. Verify if IAT2 is a separate sensor or integrated into another component before ordering parts.
• Hyundai Veloster Turbo, Sonata Turbo, Genesis Coupe (2012-2020) — The IAT2 sensor (Charge Air Temperature sensor) in the charge pipe or its wiring connector frequently causes this code.
• Kia Stinger, Forte GT, Optima Turbo (2014-2022) — Turbocharged Kia engines set this code due to a failed post-intercooler IAT sensor. Always inspect the wiring harness for damage.
• Nissan Juke (2010-2017) — A faulty transmission output speed sensor falsely triggers P0098. If transmission symptoms like harsh shifting are present, investigate the speed sensor first.
• Mercedes-Benz C-Class, E-Class, GLK, Sprinter (2009-2018) — Appears on turbocharged gasoline and diesel models due to sensor failure or wiring issues. Check Sprinter vans for chafed wiring harnesses near intake components.

Manufacturer-Specific Notes

• Ford: On EcoBoost engines, IAT2 is a frequent failure item. Transit Custom vans suffer from wires breaking right at the sensor connector due to vibration, easily spotted from under the vehicle.
• General Motors (GM): GM vehicles use two IAT sensors. IAT1 integrates into the pre-turbo MAF sensor. P0098 specifically refers to IAT2, a separate sensor in the post-turbo intake tract.
• Nissan: On the 2010-2017 Juke, a failing transmission speed sensor falsely triggers P0098 (TSB ITB12-049c). If erratic shifting is present, investigate the transmission speed sensor first.
• Volkswagen / Audi: Gen3 TSI/TFSI engines integrate the IAT2 sensor into the Manifold Absolute Pressure (MAP) sensor as a 4-pin combined unit (T-MAP sensor). Verify the temperature circuit specifically before replacing the entire unit.

Frequently Asked Questions

How much does it cost to fix code P0098?

Costs range from $0 to reconnect a plug, to $70-$225 for a sensor replacement. Wiring repairs run $110-$390 depending on the break's location. A rare PCM replacement exceeds $1,200.

I replaced the IAT sensor, but the P0098 code came back. What now?

Confirm you replaced IAT Sensor 2 (post-intercooler), not Sensor 1. Next, inspect the electrical connector for corroded pins and perform a continuity test on the signal and ground wires. A broken wire in the harness is the most likely culprit.

I just worked on my car and now have a P0098 code. What should I check first?

You likely forgot to plug the IAT Sensor 2 connector back in. An unplugged sensor creates an open circuit, instantly triggering a P0098 code. Locate the sensor on the intake piping and push the connector until it clicks.

Where is the IAT Sensor 2 located?

On turbocharged engines, IAT Sensor 2 sits in the intake tubing after the intercooler and before the throttle body. This differs from IAT Sensor 1, which is usually integrated into the Mass Airflow (MAF) sensor near the air box.

Will cleaning the IAT sensor fix a P0098 code?

No, cleaning rarely fixes a P0098 'Circuit High' code. This code indicates an electrical open circuit, such as a broken wire, unplugged connector, or internally failed sensor. Cleaning only helps slow-responding sensors, not broken circuits.

Can an aftermarket air intake cause a P0098 code?

Yes, installing an aftermarket intake triggers P0098 if the sensor wiring harness is stretched or damaged during installation. Altering the sensor's thermal environment also causes abnormal readings. Ensure the sensor mounts securely without pulling the wires tight.

What does 'Bank 1' mean in the P0098 code definition?

Bank 1 identifies the side of the engine containing cylinder number one. On inline engines, there is only one bank. For P0098, it confirms the sensor's location in the intake system serving that specific cylinder bank.

Key Takeaways

• P0098 triggers when the engine computer detects a voltage over 4.8V from Intake Air Temperature Sensor 2, indicating an open circuit like an unplugged sensor or broken wire.
• Always check for an unplugged IAT2 sensor first, especially if the code appears immediately after replacing an air filter or servicing the intercooler.
• Diagnose the fault by checking live scanner data for a stuck -40°F reading, then use a jumper wire across the connector terminals to see if the temperature jumps to 250°F+.
• Fixing this code promptly prevents a 10-15% drop in fuel economy and avoids premature catalytic converter failure, which costs up to $2,500 to replace.