Powertrain, generic · Fuel and air metering, auxiliary emission controls
P009A Intake Air Temperature/Ambient Air Temperature Correlation
Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo
After a long standstill with the engine cold, intake air temperature and ambient air temperature should be about the same. P009A is set when the two sensors disagree by more than a threshold at the next start. A detected engine block heater usually suspends the test. Several manufacturers perform this comparison under other codes; no manufacturer description naming P009A itself was found. Suspects are both sensors, an ambient sensor in a heat-affected position and contact resistance at a connector.
Likely causes
Intake air temperature sensor drifting or contaminated
Ambient temperature sensor faulty or in a heat-affected position
Contact resistance at a connector
Engine block heater or auxiliary heater distorting the comparison
Symptoms
- Check engine light on
- Usually no noticeable symptoms
Repair estimate
DifficultyMediumDIY possible
Parts and labour€40–200
Time0.5–1 h
Typical range across vehicles; the real cost depends on what the testing finds.
Parts involved
intake air temperature sensorambient air temperature sensorsensor wiring
Related codes
References: law.cornell.edu, static.nhtsa.gov, fordservicecontent.com.