BenzWorld Junior Member
Date registered: Mar 2010
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Dealer Can't Diagnose 1998 E320 Check Engine Light
Today marks my 7th visit to the dealer.
My car won't throw a code, but the light continually comes on.
The car will fault when driven at moderately cool temperatures (30-50 degrees) for about 20-40 minutes at a consistently high speed. So if I leave my house when the engine is 'cold' and drive for about 20-40 minutes, I will come to a complete stop. The engine will idle down and come to rest. When it comes to rest, the engine will shudder and the light will come on. Sometimes it shudders once and nothing happens, then it will shudder a few seconds later and the light will come on.
The car runs fine, with the light on or off.
The car, since I've had it for 5 years, will drop about 50 rpms for a split second and then will pop back up to normal idle. The car only will shudder before the light comes on.
When they tried replacing the relay, but that didn't work. The car didn't drop the 50 rpms, but would still shudder and engage the light.
They replaced a cable that involved 'cold start' and said with 99% certainty that it was the culprit, but it wasn't.
The car doesn't fail every time I drive in those circumstances, but will come on within two weeks of them resetting the light. All when I come to a complete stop after a period of warmup driving.
They've told me I can bring in my car when the light has just come on for an instant diagnostic, but I have yet to have that sync up with their shop hours and my schedule.
Anyone have any insight on to what this could be?