QuestionI have a 94 940 volvo wagon non turbo,161,000 miles check engine light comes on, sets codes 232,231,221 in that order. If I reset the codes at the obd1 terminal, the codes come back almost immediately ,if I disconnect the battery to reset, they come back after about 50 miles. so far the O2 sensor, plugs, wires, cap, rotor,coil, fuel pressure regulator,fuel injectors, fuel and air filters ,in tank fuel pump and sock ,engine temp sensor, have been replaced. all grounding points have been cleaned and checked ,fuel pressure is good, CAT is good, exhaust is not choked, the AMM, computer and ignition module have been swapped with known good units the EGR valve and system ,idle air motor, and intake manifold have been removed and cleaned. compression is good. Idles good, Vac lines are all good.Evap system good. The engine runs strong and gradually deteriorates and starts to run rich, idle drops a little and then it throws the codes. What am I missing here? What should I check next?
AnswerCharlie,
You have a lot of fuel trim codes and most times that is caused by vacuum leaks and or a bad AMM. It appears that you have tested all the known problem areas, then I would have to say if you did not miss something in your testing then possible a wire harness problem, or a bad part that was used as a tester.
