CEL comes and goes, P1123 & P1125 Lean Limit. Is Airflow Sensor

[Wonko The Sane]

Hey Gents,

I have a check engine light that seems to come on about half the time. It will pop on and stay on for a few days until it decides that it's had enough and then disappears for a few days.

According to Durametric, the error codes are P1123 and P1125 which is Oxygen Sensing Adaptation Area 1 (Cylinders 1 - 3) - Lean Threshold and Cylinders 4-6, respectively.

After reading through a few other posts with an external link to Mass Airflow Sensor cleaning instructions, it appears that my two main troubleshooting efforts should focus on either a vacuum leak around the intake plenum area or replacing the MAS.

My thoughts on it are that if it were a vacuum leak, it wouldn't go away on its own merits. Although modern cars are amazing, they don't generally mend physical failures such as cracks in the plastics and rubbers.

This singles out the MAS, but can anyone think of anything else to check before blindly go replacing it? I want to take care of this problem now before the new owner takes delivery of it.

Thanks!