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2005 Mazda 323 - Code P2177

I have a 2005 mazda 3 sp23 check engine light on. Code p 2177. I had mechanic place code reader on car and was getting sensors reading according to mechanic. Mechanic replaced a sensor in exhaust. He is lost. Can someone pls help me

P2177 MAZDA Possible Causes

  • Intake air leaks
  • Faulty front heated oxygen sensor
  • Ignition misfiring
  • Faulty fuel injectors
  • Incorrect fuel pressure
  • Lack of fuel
  • Faulty Mass Air Flow (MAF) sensor
  • Incorrect Positive Crankcase Ventilation (PCV) hose connection

How do u know what sensor is faulty

That’s a too-lean code. If the problem is a faulty sensor, then the shop would do a quick visual check that all the stuff is connected correctly, theb check each sensor one at a time. Usually they’d do a fuel trim test first, to get a clue to the extent of the problem.

You need a better mechanic. If he is lost this quickly, he will likely not fix your problem. Find a better one.


from the @Purebred list above, cleaning MAF and replacing PCV is something this old car would definitely benefit from, and both items are under $10

also, car is quite old, so it’s a good idea to check all vacuum connections, a little crack there will totally explain lean condition

I agree with @George_San_Jose1 that fuel trims are important to check to assess what’s going on, including how trims react to the increasing engine rpms

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Continuing on with my 2005 mazda 3i sp23 issues.

Car has 120k 2.3l engine. The car has check engine light still on. One mechanic replaced o2 sensor ,had mass air sensor replaced. The car was running rough. I took it to another mechanic and he replaced coils and plugs,and found oil on spark plugs. Replaced gasket and sensors. No dash has break light on, engine light and he can’t read code from computer. Suggestion was to replace com…

Can someone help me

A fuel trim test is the logical next step.