P0171 NISSAN -

Question

2001 nissan maxima, I had all oxygen sensors replaced. when the code is erased 18 miles later the code is pending. Then at the 50 miles the mil comes on. The  ecm was replaced about 5000 miles ago and the dealer replaced something on the engine because the car would not idle at all and shutdown. They replaced the ecm and the other part but about 30 days later the idle would jump up to 3000 rpm for no reason.  The dealer said they would have to reprogram the ecm and again I had to pay. I was told by the dealer ecm was bad and burnt out the other part. Car runs fine but for the Mil

Answer 1

The 171 code means there is a lean fuel mixture. This is most often causd by a faulty mass air flow sensor. They need to check for intake leaks  and check the fuel trim to determine if there is a vacuum leak on the system. If not, then it's likely a problem with the maf sensor. The maf sensor should be read using a scan tool to determine if it's the problem or not.