GM Code 44 Lean Exhaust
CODE 44 - Lean Exhaust
Trouble Code 44 indicates that the O2 sensor is showing a persistently high exhaust oxygen content (lean), despite the efforts of the ECM to increase injector on-time (thus increasing fuel delivered). Integrator and BLM numbers may indicate > 128 by a substantial margin.
The conditions for setting this code are:
- no Code 33 or Code 34 (MAF Error) present, and
- the O2 sensor voltage remains below 250 mVolts, and
- the ECM is in Closed Loop control, and
- the above conditions exist for more than 50 seconds.
Typical causes for this code include:
1) O2 sensor defective or lead shorted
2) Lean injectors (dirty or blocked)
3) Water in fuel
4) Exhaust leaks upstream of O2 sensor
5) Fuel pressure or volume too low
6) MAF sensor reading lower airflow than is actually present
7) Vacuum leaks
8) Incorrect or poorly calibrated PROM in the ECM
