129 Insufficient manifold absolute pressure or mass air flow change during dynamic response test KOER
How to read it
Code 129 reads as 1 flash, pause, 2 flashes, pause, 9 flashes on the check-engine light. Jumper the self-test input to signal return at the test connector, then run the key on engine off self test and the running self test, counting the check-engine flashes each time.
New to flash codes? The OBD-I code reading guide walks through the paperclip method, code 12, and reading two-digit codes.
What does Ford code 129 mean?
129. Insufficient manifold absolute pressure or mass air flow change during dynamic response test KOER. This code sets when your vehicle computer detects insufficient manifold absolute pressure or mass air flow change during dynamic response test koer.
Common causes of 129
- Incorrect throttle operation
- Vacuum hose damaged/disconnected
- MAP sensor
- L AC system
- ECM
How to fix 129
- Check the throttle linkage and its adjustment, and look for a sticking valve
- Check the vacuum hoses for damage, a blockage or a wrong connection
- Test the MAP sensor and replace it only if it fails its own test
- Check for L AC system
- Test the ECM last, only after every circuit test has passed
- Clear the code, then retest to confirm the fix holds