2000 ML320
Here is the saga. Last fall the CEL light came on and stayed on. There was no apparant change in performance so I didn't worry. I had the codes read and reset to no avail, the CEL came on again shortly after. The codes suggested faulty air mass sensor and oxygen sensors, both bank one and two, front. It was suggested we start with the air mass sensor because faulty codes there can trigger the oxygen sensor fault codes also.

The ML ran well, mpg actually improved and we let the sleeping dog lie. I bought a can of CRC Air Mass Cleaner and cleaned the sensor. I couldn't tell if it made any difference and the CEL stayed on. This past week I decided to try cleaning it again and disconnect the battery to clear the codes. After doing so the vehicle barely ran, worse than limp home mode and the CEL was right back on.

For about half the cost of the whole unit I ordered the air mass insert, installed it and the vehicle runs like it always did, maybe even better. The CEL is off and I did not disconnect the battery to clear it. We have driven about 400 miles since the installation and all is well. The moral of this is that I should have replaced the sensor a long time ago and used the money spent on the CRC cleaner to pay for part of the cost.

Jim W.