Intake Air Temperature Sensor 2 Circuit Range/Performance
The P0099 code means the vehicle's onboard diagnostic system has detected: Intake Air Temperature Sensor 2 Circuit Range/Performance. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $40 - $300 (parts and labor)
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Common Symptoms
- Check Engine Light illuminated
- Turbo boost may be limited
- Reduced engine performance
- Inconsistent fuel trim readings
Probable Causes (Ranked by Likelihood)
- IAT sensor 2 reading out of expected range Very High
- Damaged or contaminated sensor element High
- Intercooler leak affecting charge air temperature Moderate
- PCM calibration issue Low
Step-by-Step Diagnostic Procedure
-
Monitor IAT sensor 2 readings during a drive. Values should rise with boost pressure and drop between boost events.
-
Compare IAT1 and IAT2 readings. IAT2 should be cooler than IAT1 under boost if intercooler is working.
-
Inspect the intercooler system for leaks using a boost leak tester (pressurize to 15 psi).
-
Check sensor for contamination. Clean with electronics cleaner if oil-fouled.
Frequently Asked Questions
What does range/performance mean for P0099?
The sensor is providing readings but they are outside the expected range for current operating conditions. The value may be too high, too low, or not responding quickly enough to temperature changes.
Can an intercooler problem cause P0099?
Yes, a leaking or inefficient intercooler can cause charge air temperatures outside the expected range, triggering P0099.
Does P0099 limit turbo boost?
Some PCM calibrations will reduce turbo boost when IAT2 readings are unreliable, as a protective measure against engine knock from overheated charge air.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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