P2173
OBD-II Diagnostic Code
Severity: ModerateWhat it means
P2173 means the ECM detected more airflow through the throttle body than expected for the throttle position.
This usually indicates a vacuum leak, stuck-open throttle, or faulty throttle position sensor.
Check for vacuum leaks first.
Affected Models
- All OBD-II vehicles with electronic throttle control (2002+)
Common Causes
- Vacuum leak after the throttle body
- Throttle body plate not closing fully (carbon buildup)
- Throttle position sensor reading incorrectly
- Air leak in the intake manifold gasket
- PCV valve stuck open
How to Fix It
-
Check for vacuum leaks.
Listen for hissing sounds around the intake manifold.
Spray carburetor cleaner around vacuum lines — a change in RPM indicates a leak. -
Clean the throttle body.
Carbon buildup prevents the throttle plate from fully closing, allowing air to bypass it.
-
Check the PCV valve.
A stuck-open PCV valve allows extra air into the intake.
Frequently Asked Questions
Is P2173 dangerous?
Not immediately, but the engine may idle high or surge.
The ECM compensates by reducing fuel, but this can cause lean running if severe.
Can a dirty throttle body cause P2173?
Yes.
Carbon buildup on the throttle plate prevents it from fully closing, allowing more air than expected past the closed throttle.