Check engine light (CEL) is on. The vehicle is a 98 ML-320.

A dump of the computer's error codes indicates that I have two problems.

The first is "Injector Circuit - Cylinder 12."
The second is "Engine Shutoff Solenoid."

The Cylinder 12 code is a real stumper. I can find but 6 cylinders under the hood. Where did those Alabamaniacs put the other 6?

As for the Engine Shutoff Solenoid, I can not identify this part.

I can find two "Engine Shut-off Valves. " These, however, are not solenoids but vacuum valves. They appear to be working normally.

Does anyone have a clue as to what is wrong with my engine? I have reset the CEL now three times. The time and mileage between resets varies. It seems the CEL comes on after going over a speed bump in a parking lot.

By the way, the engine appears to be preforming just fine. Power, acceleration, gas mileage, appear normal. Idle speed may be low (600 rpm), conditions are engine is hot, idling in gear, brake on.

What OB2 codes did you get? and when you drive the vehicle.. can you describe any difference with acceleration or etc.??

tabo:

These are the codes I got from the OBD II scanner:

1. P0212. "Injector Circuit - Cylinder 12."
2. P0215. "Engine Shutoff Solenoid."

What little I have been able to glean from the internet is that the engine shutoff solenoid is typically assocated with a diesel fueled vehicle... Where is it on this engine? I guess I need a book...

As for the cylinder 12 error, the only think I can think of is the dual spark plugs per cylinder. Could one of them be coded as "cylinder 12."

Regarding performance, I have seemingly noticed no difference in power output. The engine accelerates briskly. Idle "seems" a bit unstable, however, especially as the AC compressor cycles on and off. There is a "slight" stumble in idle speed when the compressor clicks on. Engine idles about a needle width above 500 rpm.

The OBD II scanner had bad software. With new software it now reads the following codes...

P0170 and P0173 (Fuel trim, bank 1 and 2).

As we well know.... A faulty mass airflow sensor.

At one point, I thought "old" friends at EPA had stuffed 6 more cyinders under the hood to make life miserable for me when I went for a smog test... all in revenge for escaping from NOVA... George Allen... a US Senator... you've go to be kiddin!