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i have 02 mazda protege ,check engine light on with code ...

Sent to Car Experts February 29 6:54 p.m.

i have 02 mazda protege ,check engine light on with code po171 ( system fuel lean ,bank ) no vacum leaks ,no misfire.car has 70000 miles ,do you think tune up and good set of wires may taking care problem,or may be upstream O2 sensor need to be replace ?

Optional Information:
2002 Mazda protege 4cyl

Already Tried:
nothing

Customer (name blocked for privacy)

Status: Closed Value: $15

Answer
February 29 7:09 p.m. (15 minutes and 4 seconds later)

ACCEPTED

Hi there!This code can be caused by a bad mass air flow sensor or a bad rear O2 sensor.low fuel pressure can do the same.Because the car appears to be running good,I think you likley need the rear o2.This code is a bit tricky because it makes you think the problem is with the front O2,but 95% of the time it's caised by something else.To properly diagnose it you really need a scan tool.Shooting from the hip I would say the rear O2 is your problem.Hope this helps!Thanks

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