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P2199 – Intake Air Temperature Sensor 1/2 Correlation (OBD2)

P2199 means "Intake Air Temperature Sensor 1/2 Correlation". Two signals that should agree with each other no longer match. The control unit cannot tell which one is wrong, so it stores a correlation fault for the intake air temperature (IAT) sensor.

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P2199 quick summary

Fault codeP2199
MeaningIntake Air Temperature Sensor 1/2 Correlation
SystemPowertrain (Engine & Transmission)
VehiclesGeneric OBD2
SeverityLow
Can I drive?Yes. The engine uses a substitute temperature, so you may notice slightly harder starting or higher fuel consumption. Have it fixed at the next opportunity.
Repair cost€15 – €200

How the intake air temperature sensor works

The intake air temperature sensor tells the engine control unit how warm the incoming air is, so it can correct the fuel quantity, ignition timing and boost for the air density.

The IAT sensor is a thermistor (NTC resistor): its resistance falls as the temperature rises. It is often built into the MAF sensor or MAP sensor, or mounted separately in the intake duct or intake manifold. Engines with a turbocharger frequently have a second intake air temperature sensor after the intercooler (IAT 2), which is why codes for sensor 2 exist.

Cold air is denser and contains more oxygen than warm air, so the control unit adds fuel when it is cold and retards ignition when the intake air is very hot to prevent knocking. A wrong IAT signal does not usually cause dramatic symptoms, but it affects starting, fuel consumption and emissions.

Codes like P0127 (intake air temperature too high) are not electrical faults but a warning that the measured temperature is really too high – for example because of a blocked intercooler or hot air being drawn in from the engine bay.

Symptoms of P2199

  • Check Engine light on
  • Slightly harder cold or hot starting
  • Higher fuel consumption
  • Reduced power or knocking in hot weather (P0127)
  • Often no noticeable symptoms at all

Most common causes of P2199 (most likely first)

Mechanic's Pro Tip

Compare the IAT reading with the coolant temperature after the car has stood overnight. If they differ by more than about 5 °C on a cold engine, one of the two sensors is wrong – this simple check avoids replacing the wrong part.

  1. 1.One of the two sensors is faulty or drifting

    Most likely

  2. 2.Mechanical cause

    For example a stretched timing chain, a wrong installation or a leak that really makes the two values differ.

  3. 3.Wiring fault on one of the two signals

  4. 4.Damaged wiring or corroded connector

    Common where the sensor sits in the air duct and the connector gets wet.

  5. 5.Sensor dirty or coated with oil

    An oily sensor reacts slowly to temperature changes.

  6. 6.Intercooler blocked or hot air intake (P0127)

    A dirty intercooler, a missing intake duct or an air box drawing hot engine-bay air makes the air really too warm.

  7. 7.Fault in the control unit

    Rare, but possible when wiring and sensor test fine.

Step-by-step diagnostic guide

  1. 1

    Read codes and live temperature

    Read all codes and look at the intake air temperature in live data. On a cold engine that has stood overnight, the IAT should match the outside air and coolant temperature within a few degrees.

  2. 2

    Compare both signals side by side

    Display both values together in live data (or on a two-channel oscilloscope) and see which one is out of line with the actual conditions. Fix that signal or the mechanical cause first.

  3. 3

    Check for implausible values

    A reading of around –40 °C usually means an open circuit; a reading of +130 °C or more usually means a short to ground. A reading that is realistic but wrong points to the sensor itself.

  4. 4

    Measure the sensor resistance

    Unplug the sensor and measure its resistance at a known temperature, then warm it gently with a hairdryer – the resistance must drop smoothly.

    Multimeter: Typical NTC values: roughly 2–3 kΩ at 20 °C and a few hundred ohms at 80 °C (check the exact table for your sensor).

  5. 5

    Check wiring and connector

    Check the reference and ground wires for continuity and the connector for corrosion or water.

  6. 6

    Replace the sensor or fix the hot-air cause

    Replace the sensor if its resistance is wrong. For P0127, clean the intercooler, check the intake ducting and make sure the engine is not drawing hot engine-bay air.

How do I read fault codes? →Where the OBD2 port is, which scanner to use and how to read and clear codes step by step.

Frequently asked questions

Can I keep driving with P2199?

Yes. The engine uses a substitute temperature, so you may notice slightly harder starting or higher fuel consumption. Have it fixed at the next opportunity.

How much does it cost to fix P2199?

Typical repair costs are 15 € – 200 €, depending on the cause and the vehicle. The most common fixes are: one of the two sensors is faulty or drifting; mechanical cause; wiring fault on one of the two signals. Always confirm the cause with the tests above before buying parts.

Where is the intake air temperature sensor?

It is usually built into the MAF sensor or the MAP sensor, or screwed into the air duct or intake manifold. Turbo engines often have a second sensor after the intercooler.

Does a bad IAT sensor cause poor fuel economy?

It can. If the sensor reports colder air than reality, the engine injects more fuel than needed. The effect is usually small but noticeable over time.

What is the difference between P2199 and similar codes?

P2199 belongs to a group of codes for the same component that differ in the type or location of the fault: P0110 – Intake Air Temperature Circuit Malfunction; P0111 – Intake Air Temperature Circuit Range/Performance Problem; P0112 – Intake Air Temperature Circuit Low Input; P0113 – Intake Air Temperature Circuit High Input; P0114 – Intake Air Temperature Circuit Intermittent; P0127 – Intake Air Temperature Too High. The tests on this page apply to the whole group; the type of fault tells you where to start.

Related fault codes

This guide is for information only. Working on vehicles can be dangerous — if you are unsure, have the car checked by a qualified mechanic. Values can differ between model years; always check the manufacturer's repair information.