P0098: Intake Air Temperature Sensor 2 Circuit High

P0098 means the circuit for the second intake air temperature sensor is reading too high a voltage, which the ECU translates into an implausibly cold air reading, usually around -40 C. The sensor is an NTC thermistor whose resistance rises as it gets colder, so an open circuit or an unplugged connector looks exactly like extreme cold. On most turbocharged and supercharged engines this sensor sits in the charge air pipe after the intercooler, often built into the boost pressure sensor, and it tells the ECU how hot the compressed air entering the engine really is. A connector reseat, a new sensor, or a wiring repair typically costs 15 to 230 euros.

P0098 is a emissions-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0098 and illuminates the check engine light.

If your vehicle has triggered P0098, you may notice one or more of these symptoms:

• Check engine light illuminated
• The second intake air temperature value in live data sits pinned at its minimum, around -40 C, even on a warm engine
• Softer acceleration under boost, because the ECU falls back to a default charge air temperature and takes a cautious approach to fuelling and timing
• Slight hesitation or a rough idle, most noticeable in the first minutes after a cold start
• Marginally higher fuel consumption
• Boost pressure or fuel trim codes stored alongside P0098 on some engines

Here are the most common causes of P0098:

Generally yes, for short-term driving. Usually safe to drive in the short term. The ECU loses the second intake air temperature reading and falls back to a default value, so on turbocharged and supercharged engines it fuels and times conservatively and may hold back boost. Expect softer acceleration and slightly worse economy rather than a breakdown. Fix it within a few weeks so the engine is not running on a guessed charge air temperature.

Follow these steps to pinpoint the root cause of P0098:

1. With the engine off after a night parked, read both intake air temperature values in live data. They should agree within a few degrees. If sensor 2 sits at its minimum of about -40 C while sensor 1 shows the real ambient temperature, the circuit is open rather than genuinely cold
2. Find the sensor. On turbocharged and supercharged engines it is normally in the charge air pipe between the intercooler and the throttle body, and on many cars it is built into the boost pressure sensor in that same pipe. Some engines instead place it in the intake manifold
3. Unclip the connector, look for corrosion, spread or backed out pins and water inside, then clean it and push it back on until it clicks. Wiggle the plug and the first stretch of harness while watching the live reading, since a value that jumps back to a sensible number points at the connector
4. Work out which pin is which before you probe anything. A standalone temperature sensor has two pins, one signal and one sensor ground. A combined charge air pressure and temperature sensor has four, carrying a 5 volt reference, a sensor ground, a pressure signal and a temperature signal, so on those you have to identify them first. Take the pinout from a wiring diagram for your exact engine, and if you cannot tell the pins apart with confidence, stop here and let a workshop do the next two steps. Then turn the ignition on with the engine off, unplug the connector and measure the voltage between the temperature signal pin and the sensor ground pin. Around 5 volts confirms that the supply and the sensor ground both reach the plug. No voltage means the supply or the ground side is open before you even get to the sensor
5. This is the step that separates a bad sensor from a broken wire, and it is the one step where the wrong pin does real damage. Leave the connector unplugged with the ignition on and bridge the temperature signal pin to the sensor ground pin only, using a short jumper wire. Never bridge the 5 volt reference pin to ground: the ECU feeds that same reference to other sensors, and shorting it can turn one fault code into a dashboard full of them. If the live reading jumps to its maximum, roughly 120 to 150 C, then the wiring and the ECU are fine and the sensor itself is faulty. If the reading stays at -40 C, the sensor is innocent and the fault is in the harness or at the ECU
6. Confirm the verdict. Measure the sensor across its terminals with a multimeter, where a healthy NTC reads roughly 2,000 to 3,000 ohms at 20 C and an infinite reading proves it is open internally. If the jumper test pointed at the harness instead, check continuity of the signal and sensor ground wires back to the ECU connector and repair the break

Repair costs for P0098 vary depending on the root cause and your vehicle. Here are typical estimates:

P0098 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:

These codes are often seen alongside P0098 or indicate related issues: