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P0099 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


P0099 is an OBD II error code indicating an issue with the intake air temperature sensor, circuit IntermittentErratic. A major component for the data transmission of incoming air temperatures to the engine control panel is an intake air temperature sensor, or IAT.


The P0099 code is triggered when the powertrain control module (PCM) detects intermittent or erratic voltage signals from the Intake Air Temperature Sensor 2. In order to optimize performance, the PCM is based on this sensor’s information about air-fuel mixture, ignition timing, and other engine parameters.


Several factors can lead to the activation of the P0099 code, including:

  • Faulty Intake Air Temperature Sensor: A malfunctioning or damaged IAT sensor can provide inconsistent temperature readings, leading to intermittent or erratic voltage signals.
  • Wire Problems: The IAT sensor’s signal may be interrupted by corroded or damaged wires and connections.
  • Sensor Position: The IAT sensor may give inaccurate results if it is positioned incorrectly or placed in an area where it is exposed to extreme heat or cold.
  • PCM Malfunction: A malfunctioning powertrain control module might result in inconsistent IAT sensor readings and set off the code.


You could encounter the following signs and symptoms when the P0099 code is present:

  • The Check Engine Light Is On: The check engine light on the dashboard of the car is the first obvious sign.
  • Diminished Engine Performance: Due to incorrect air-fuel mixture changes, the engine may show diminished power and performance.
  • Poor Fuel Efficiency: Poor fuel efficiency can be caused by inaccurate sensor readings that result in inefficient fuel burning.


An OBD-II scanner or a certified mechanic must follow a step-by-step procedure to properly diagnose the P0099 error code. Typically, the diagnosis entails:

  • Code Reading: Using an OBD-II scanner, retrieve the P0099 code and any associated codes.
  • Visual Inspection: Look for any rust or obvious damage in the wiring and connections of the IAT sensor.
  • Sensor testing: Check the resistance and voltage output of the IAT sensor to see if it complies with the manufacturer’s requirements.
  • Check for PCM Issues: Examine the PCM and its connections for any potential problems.

Common mistakes

Dealing with the P0099 error code might result in errors like these:

  • Ignoring the Code: Ignoring the P0099 code and the check engine light might cause the engine to run less efficiently and perhaps endanger other engine parts.
  • Replacing the Sensor Without Proper Testing: If the fundamental cause is elsewhere, replacing the IAT sensor without first confirming its operation might result in excessive costs.
  • Ignoring Wiring Problems: Failing to search for corroded or broken wiring might lead to incorrect identification of the issue.

How serious is this?

While the P0099 code may not result in immediate vehicle failure, it has to be taken into account. A prolonged failure to remedy this could result in diminished engine performance, reduced fuel efficiency, and the risk of damage to the rest of the engine components.

What repairs can fix the code?

repair manuals

Possible fixes for the P0099 error code include:

  • Replacing the Intake Air Temperature Sensor: If the present IAT sensor is broken or defective, install a new one.
  • Fixing or replacing the wiring and connectors: Take care of any wiring and connection problems with the IAT sensor.
  • Moving the IAT Sensor: If the sensor’s placement results in sporadic or inconsistent readings, think about moving it to a better spot.
  • PCM Reprogramming or Replacement: If the PCM isn’t working properly, it may need to be reprogrammed or replaced.

Related codes

Other related codes that may accompany or be triggered by P0099 include:

  • P0096 – Intake Air Temperature Sensor 2 Circuit Range/Performance
  • P0097 – Intake Air Temperature Sensor 2 Circuit Low Input
  • P0098 – Intake Air Temperature Sensor 2 Circuit High Input


Finally, the P0099 DTC code indicates that there is a potential problem with the Intake Air Temperature Sensor 2 Circuit Intermittent and Erratic. It would help to maintain optimal engine performance, fuel efficiency, and overall vehicle reliability in a timely manner by addressing this problem. Seek the assistance of a qualified technician to diagnose the root cause accurately and perform the necessary repairs if you encounter a check engine light with a P0099 code.

If you are able to understand the meaning, causes, signs, and possible repair of the P0099 code, you can take steps toward keeping your vehicle in working order as effectively as possible. A key to prolonging the life of your vehicle and avoiding major problems before they happen is proper maintenance and timely repairs.

P0099 Code – What Does It Mean & How To Fix It