Now my car (95 E320, 71K) is giving me the pin 8, code 13 problem. This is in addition to the pin 2, code 3 (Lambda control faulty).

I've replaced the O2 sensor, air mass meter, checked for vacuum leaks, and checked for fuel in the fuel pressure regulator vacuum line. Codes were erased before rereading to prevent reading spurious codes. Wiring harness was replaced some time ago. The car runs fine, except that the air pump runs constantly and my gas mileage is down (21 mpg, mixed driving).

I changed the air mass meter because I was getting pin 2, code 4 (Air injection system faulty hot film mass air flow sensor with hot wire). Now I get code 3. Pin 8, code 13 hasn't changed.

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95 E320 Cabriolet, 169K