How serious is this DTC?
The IAT sensor input is essential for fuel delivery and ignition timing. A stored P2199 code should be treated as serious.
What are some symptoms of the code?
Symptoms of a P2199 trouble code may include:
- Decreased engine performance
- Reduced fuel efficiency
- Hesitation during acceleration
What are some common causes of the code?
Causes of this code may include:
- Disconnected IAT sensor
- Faulty IAT sensor
- Restricted air filter
- Open or shorted circuits or connectors
- PCM programming error or faulty PCM
What are the troubleshooting steps for P2199?
Start with an inspection of the air filter element. It should be inserted into the housing as intended—without dirt or debris.
If the air filter element is relatively clean and installed correctly, perform a visual inspection of the IAT sensor system wiring and connectors.
A diagnostic scanner, infrared thermometer (with a laser pointer), digital volt/ohmmeter (DVOM), and a reliable vehicle information source will be needed to diagnose a P2199.
At the end of a visual inspection, connect the scanner to the vehicle’s diagnostic port and retrieve all stored codes and freeze frame data. Note this information for later. Clear the codes and test the vehicle to see if P2199 resets.
Obtain diagnostic flowcharts, wiring diagrams, connector pinout diagrams, component testing procedures/specifications, and connector face views from your vehicle information source. This type of information, in addition to applicable technical service bulletins, can be crucial in the diagnostic process.
Disconnect the PCM (and any associated controllers) before testing individual system circuits with the DVOM. This will help prevent damage to the controller.
Test each IAT sensor:
- Use the DVOM to test the IAT sensors
- Set the DVOM to the ohms setting
- Disconnect the sensor being tested
- Follow the manufacturer’s component testing specifications
- Sensors that do not meet testing specifications should be considered faulty
Test the reference circuit:
- Use the DVOM to test the reference voltage (typically 5 V)
- With the key on and engine off (KOEO), disconnect each IAT sensor connector
- Using the DVOM’s positive test lead, probe the reference circuit pin of the IAT sensor connector
- Simultaneously, probe the ground pin with the DVOM’s negative test lead
- The reference voltage should be detected
- If not, test the same circuit at the PCM connector. If no reference voltage signal is detected there, suspect a PCM issue or programming error.
Test each IAT sensor signal circuit:
- Test each IAT sensor signal circuit using the DVOM
- Plug in the IAT sensor
- Use the DVOM’s positive test lead to probe the signal circuit of each sensor
- The negative test lead should be connected to a chassis or engine ground
- The infrared thermometer will be used to verify the actual IAT
- Compare individual IAT sensor signal voltage levels at the sensor connectors with the actual IAT as reflected on the infrared thermometer
- Use the temperature-to-voltage chart (found in the vehicle information source) to determine if each sensor is functioning properly
- This is achieved by comparing individual IAT sensor data (collected in step 6 of the previous section) with the desired IAT voltage (reflected on the temperature-to-voltage chart).
If any IAT sensor does not reflect the appropriate voltage level (according to the temperature-to-voltage chart), suspect it is faulty.
If both the IAT and ambient air temperature sensor signal circuits reflect the appropriate voltage:
- Use the DVOM to test the signal circuit (for the sensor in question) at the PCM connector
- Consider there is an open circuit between the IAT and PCM if there is a proper sensor signal at the sensor connector but not at the PCM connector
- Applicable Technical Service Bulletins (TSBs) will likely assist in your diagnosis