The CEL has come back on twice since the origional post. Both times codes 2(o2 sensor) and 5(egr faulty). It does have 125,000 on the clock. Could a bad oxygen sensor cause the egr code? If it is the o2 sensor, what is the most obvious place to start. How many o2 sensors are on a 1995 e320? Should I replace all of them or is there one that is most prone to failure? There is no noticeable change in the car and when I clear the codes the light might stay off for a couple of hundred miles. When it does come on it usually comes on at a warm start. Thank you again.

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tgmiller77
1997 Land Rover Discovery 158,000
1995 E320 Wagon 132,000mi
1999 E320 Wagon 97,000mi