P0098 – Intake Air Temperature Sensor 2 Circuit High

P0098 is an OBD-II trouble code that points to a problem with your intake air temperature sensor circuit, specifically that the signal is reading higher than expected. In plain language, your engine computer thinks the incoming air temperature reading is out of range on the “too hot” side. This can be caused by a bad sensor, wiring issues, or sometimes a failing ECU. If you recently scanned your car and found P0098, this guide will walk you through what it means, the symptoms, how to diagnose it, and what it usually costs to fix.

What Does P0098 Mean?

P0098 stands for “Intake Air Temperature Sensor 2 Circuit High.” The “high” part means the ECU is seeing a higher-than-normal voltage from the intake air temperature (IAT) sensor 2 circuit. Most IAT sensors are negative temperature coefficient (NTC) thermistors, so when temperature appears very hot, the sensor’s resistance drops and the ECU sees a higher voltage signal.

On many vehicles, “Sensor 2” refers to an additional IAT sensor located after the turbocharger, in the intake ducting, or integrated into the mass airflow (MAF) sensor. When the reading is out of the expected range, the ECU sets P0098 and may switch to a backup strategy, which can affect drivability and fuel economy.

Quick Reference

  • Code: P0098
  • Definition: Intake Air Temperature Sensor 2 Circuit High
  • System: Fuel and air metering / intake system
  • Severity: Moderate – can affect drivability and fuel economy
  • Typical causes: Faulty IAT sensor, wiring issues, connector damage, rare ECU fault

Real-World Example / Field Notes

In the shop, I see P0098 most often on turbocharged engines and late-model vehicles that use multiple air temperature sensors. A common scenario: the car comes in with the check engine light on, mild hesitation on acceleration, and sometimes poor cold starts. The owner says it runs “okay” but not quite right. After scanning, P0098 shows up, and a quick inspection usually reveals a cracked IAT sensor housing, oil contamination in the connector, or a harness rubbed through near the air intake tube or intercooler piping.

On some trucks and diesel engines, the sensor sits in a hot, oily environment. Heat and vibration slowly break down the sensor and wiring insulation. You might clear the code and it comes right back as soon as the engine warms up and the ECU sees that out-of-range temperature reading again. Fixing the actual cause, not just clearing the code, is key to avoiding long-term fuel and performance issues.

Symptoms of P0098

  • Check engine light on: The MIL (Malfunction Indicator Lamp) will be illuminated and P0098 will store as a current or pending code.
  • Poor fuel economy: Incorrect intake air temperature data can cause the ECU to enrich or lean the mixture, hurting MPG.
  • Rough idle or hesitation: You may feel stumbling, hesitation, or a rough idle, especially when the engine is cold.
  • Hard starting: The engine may crank longer than normal, particularly in cold weather, due to incorrect fuel calculations.
  • Reduced power: The ECU may limit power or alter boost control on turbocharged engines as a protective measure.
  • Black exhaust smoke (some diesels): Over-fueling from incorrect temperature readings can cause visible smoke.
  • Fan or cooling behavior changes: In some vehicles, abnormal temperature data can affect when cooling fans turn on.

Common Causes of P0098

Most Common Causes

  • Failed intake air temperature sensor 2: Internal failure of the thermistor element or sensor electronics is the number one cause.
  • Open circuit in the IAT wiring: A broken wire, corroded splice, or disconnected plug can cause a high-voltage signal.
  • Damaged or loose connector: Bent pins, corrosion, oil intrusion, or a partially unplugged connector can skew the signal.
  • Harness damage near the intake tract: Wiring rubbing on metal brackets or plastic edges near the airbox or intercooler pipes is very common.
  • Sensor contamination: Heavy oil, dirt, or coolant contamination on the sensor tip can affect readings and cause erratic voltage.

Less Common Causes

  • Short to voltage: The signal wire contacting a 12V source or another circuit can force the reading high.
  • Faulty MAF/IAT combo sensor: On vehicles where the IAT is built into the MAF, a failing MAF assembly can trigger P0098.
  • ECU internal fault: Rare, but a damaged engine control unit input circuit can misinterpret the sensor signal.
  • Aftermarket modifications: Poorly installed cold air intakes, tuning devices, or relocated sensors can cause wiring strain and incorrect readings.
  • Previous repair errors: Incorrect sensor replacement, wrong part number, or pins swapped in the connector can all lead to this code.

Diagnosis: Step-by-Step Guide

You’ll want a basic scan tool, a good digital multimeter, and ideally a wiring diagram for your specific vehicle. An infrared thermometer is helpful to compare actual intake air temperature to what the ECU is seeing. If you have an advanced scan tool that can read live data and Mode $06, that makes diagnosis even easier.

  1. Confirm the code and check for others. Scan the vehicle and record all stored and pending codes. If you see related IAT, MAF, or boost pressure codes, diagnose them together, as they may share wiring or a sensor assembly.
  2. Look at live data. With the engine cold, compare the Intake Air Temp 2 reading to ambient temperature and to the main IAT sensor. They should be close. If IAT 2 shows an extremely high or unrealistic value, that supports a circuit high issue.
  3. Perform a visual inspection. Locate the IAT 2 sensor (often in the charge pipe, intake manifold, or MAF housing). Check the connector for corrosion, broken locks, oil or coolant contamination, and inspect the harness for rub-through, cuts, or previous repairs.
  4. Wiggle test the harness. With the engine running and live data displayed, gently move the harness and connector. If the IAT 2 reading jumps around, you likely have an intermittent wiring or connector problem.
  5. Check sensor resistance. With the key off and sensor unplugged, measure resistance across the sensor terminals. Compare to factory specs at a known temperature. A sensor reading open (infinite resistance) or far out of range is faulty.
  6. Verify reference voltage and ground. With the connector unplugged and key on, use the multimeter to check for proper 5V reference and a solid ground at the IAT 2 connector. If either is missing, trace the circuit back toward the ECU.
  7. Check for short to voltage. If the signal wire shows battery voltage when it shouldn’t, you may have a short to power. Inspect the harness for contact with other circuits or damaged insulation.
  8. Backprobe the signal wire. With the sensor plugged in, backprobe the signal wire and compare voltage to the scan tool reading. Slowly warm the sensor area (hair dryer, not open flame) and confirm voltage changes smoothly.
  9. Use Mode $06 if available. Some scan tools will show test results for the IAT sensor circuit. This can help confirm if the circuit is intermittently failing even when the code is not active.
  10. Rule out ECU issues last. Only after verifying the sensor, wiring, power, and ground should you suspect the ECU. At that point, professional testing or ECU substitution may be needed.

Pro tip: On vehicles with both IAT 1 and IAT 2, always compare their readings at cold start. If one reads wildly different from ambient while the other looks normal, you’ve just narrowed the fault to that specific sensor or its wiring.

Possible Fixes & Repair Costs

Most P0098 repairs are straightforward once you pinpoint the cause. Common fixes include replacing the IAT 2 sensor, repairing or replacing damaged wiring, cleaning or replacing a corroded connector, or replacing a combined MAF/IAT assembly. In rare cases, an ECU repair or replacement is needed.

Typical repair costs vary with the vehicle and labor rates. An IAT sensor replacement usually runs $75–$250 parts and labor. A MAF/IAT combo sensor can range from $200–$500. Wiring repairs may cost $100–$300 depending on access and how much harness needs to be repaired. ECU-related repairs are the most expensive, often $600–$1,200 or more. Factors that affect cost include vehicle make, sensor location, dealership vs. independent shop, and whether additional diagnosis time is required.

Can I Still Drive With P0098?

In most cases, you can still drive with P0098 without immediate engine damage, but it’s not ideal to ignore it. The ECU may run on default intake air temperature values, which can cause poor fuel economy, rough running, and reduced performance. On turbocharged or diesel engines, incorrect air temperature data can also affect boost control and emissions systems. If the car runs very poorly, stalls, or shows other serious symptoms, you should avoid driving and have it checked as soon as possible.

What Happens If You Ignore P0098?

If you ignore P0098 for a long time, you risk carbon buildup from incorrect fueling, accelerated wear on spark plugs and O2 sensors, and potential damage to catalytic converters from running too rich. On some engines, chronic incorrect temperature data can contribute to detonation or overheating under heavy load. You’ll also likely live with poor drivability and higher fuel costs, so it’s worth fixing sooner rather than later.

Need wiring diagrams and factory-style repair steps?

Powertrain faults often require exact wiring diagrams, connector pinouts, and guided test steps. A repair manual can help you confirm the cause before replacing parts.

Factory repair manual access for P0098

Check repair manual access

Compare nearby sensor intake trouble codes with similar definitions, fault patterns, and diagnostic paths.

  • P0073 – Ambient Air Temperature Sensor Circuit High
  • P2963 – Intake Air Metering Control Valve Position Sensor Circuit High
  • P0099 – Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic
  • P0097 – Intake Air Temperature Sensor 2 Circuit Low
  • P0096 – Intake Air Temperature Sensor 2 Circuit Range/Performance
  • P0095 – Intake Air Temperature Sensor 2 Circuit

Key Takeaways

  • P0098 means the ECU sees an abnormally high signal from the intake air temperature sensor 2 circuit.
  • Most issues come down to a bad sensor, damaged wiring, or a corroded connector, not a bad ECU.
  • Symptoms include a check engine light, poor fuel economy, rough running, and sometimes reduced power.
  • Diagnosis involves checking live data, inspecting the sensor and wiring, and verifying voltage, ground, and resistance.
  • Repairs are usually affordable if caught early, and fixing the problem helps protect fuel system and emissions components.

Vehicles Commonly Affected by P0098

P0098 shows up across many brands because it’s a generic OBD-II code, but it’s especially common on vehicles with turbocharged engines and multiple intake air temperature sensors. You’ll often see it on Ford EcoBoost trucks and SUVs, GM trucks and crossovers, Volkswagen and Audi turbo models, BMW and Mercedes-Benz turbo engines, and various Hyundai, Kia, and Subaru turbocharged vehicles. Diesel pickups from Ford, GM, and Ram also use multiple IAT sensors in the charge air system, making them frequent visitors to the shop with this code.

FAQ

Can I clear P0098 and keep driving if the car feels fine?

You can clear the code, but if the underlying issue isn’t fixed, P0098 will usually return. Even if the car feels okay, the ECU may be compensating, and you could be wasting fuel or stressing other components. It’s better to diagnose and repair the cause rather than repeatedly clearing the code.

Is P0098 caused by a bad mass airflow sensor?

It can be, depending on your vehicle. On many cars, the intake air temperature sensor is built into the MAF housing. In those cases, a failing MAF can trigger P0098. However, the problem could also be limited to the IAT portion or its wiring, so testing before replacing the MAF is important.

How do I know if the IAT 2 sensor or the wiring is bad?

Use live data and a multimeter. If the IAT 2 reading is unrealistic and the sensor’s resistance is out of spec, the sensor is likely bad. If resistance is good but you’re missing 5V reference, ground, or see a short to voltage on the signal wire, the wiring or connector is the issue. A wiggle test while watching live data is very helpful.

Can a dirty air filter or intake cause P0098?

A dirty air filter alone usually won’t cause P0098, but heavy contamination, oil-soaked filters, or debris that reaches the sensor can. If oil or dirt coats the IAT sensor tip or gets into the connector, it can affect the signal and trigger this code. Inspect and replace the filter if it’s heavily soiled and clean the sensor area as needed.

Does P0098 always mean I need a new sensor?

No. While a failed sensor is common, you should always inspect wiring, connectors, and related components first. Many P0098 issues are fixed by repairing a broken wire, cleaning a corroded connector, or correcting a previous repair. Replace the sensor only after confirming it’s actually out of spec.