CHECK ENGINE LIGHT

  • Tiny
  • Bcmullen95
  • 1997 GEO METRO
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 120,000 MILES

97 Geo Metro Mil Light on, inspection paper says no fault codes, fail mil light on. Any ideas?

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Wednesday, May 4th, 2011 AT 3:06 PM

21 Replies

  • Tiny
  • Wrenchtech
  • EXPERT
  • 20,567 POSTS

That's not usually possible.
The "check engine" light is an indicator for a system that monitors many electronic functions in the system, also called the "malfunction indicator lamp" (MIL). It can come on for any of hundreds of different causes from any of the systems that the computer monitors. Some are very important and can lead to further component or engine damage and some are emissions related not as serious but still a problem and need to be repaired.

Your first step is to have the computer scanned to retrieve the trouble codes that were set when the check engine light came on. Those codes will give you specific information about what the computer saw and will get you pointed in the right direction to find your problem. With a 1996 or newer and some 95 cars and you have an AutoZone or Advanced auto parts in your area, they will read them for free. Once you have these code numbers, we can be a lot more specific about what your problem may be.

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Wednesday, May 4th, 2011 AT 3:45 PM
  • Tiny
  • Bcmullen95
  • MEMBER

Found out the code is p0420. Any best way to diagnos this code. I know that it deal with the O2 sensors, exhaust leak, or catyltic converter. Anything else I might want to check out.

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Friday, May 6th, 2011 AT 6:46 PM
  • Tiny
  • Wrenchtech
  • EXPERT
  • 20,567 POSTS

That is going to be a bad Catalytic Converter on Bank 1. It is rarely anything else.

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Friday, May 6th, 2011 AT 7:24 PM
  • Tiny
  • Bcmullen95
  • MEMBER

O2 sensor at bank 2 is reading 1.275 and does not fluctuate at all. I even unplugged it and same reading. What would cause that?

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Saturday, May 7th, 2011 AT 10:05 PM
  • Tiny
  • Wrenchtech
  • EXPERT
  • 20,567 POSTS

You don't even have a problem on bank2. Why are you messing with that?

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Saturday, May 7th, 2011 AT 10:26 PM
  • Tiny
  • Bcmullen95
  • MEMBER

Aren't the main reasons that the code will show up is from an exhaust leak, O2 sensors, or bad catalytic converter? Are you telling me that bank 2 will allways have the same reading reguardless of wear it is in the exhaust pipe or out of the exhaust pipe? From research I read that what can cause the code is both Oxygen sensors reading the same number. That is true correct? I am trying to narrow down and illiminate the other possibilities first. I know that I have an exhaust leak on the manifold and just at the flange. What should the readings be for th O2 sensor at bank 2? To answer your question I want to narrow down or eliminate all possibilities before I go and spend $200 on a new catalytic converter and find out that it did not resolve the problem.

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Sunday, May 8th, 2011 AT 12:33 AM
  • Tiny
  • Wrenchtech
  • EXPERT
  • 20,567 POSTS

The computer is not seeing a problem on that side so you're just not reading it right. Your problem is on the other side.

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Sunday, May 8th, 2011 AT 12:36 AM
  • Tiny
  • Bcmullen95
  • MEMBER

Explain how I am not reading it right. Are you telling me that my scan tool is faulty? Bank one it fluating as I have read it should. Isn't bank 2 suposed to flucuate a little?

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Sunday, May 8th, 2011 AT 12:42 AM
  • Tiny
  • Wrenchtech
  • EXPERT
  • 20,567 POSTS

It has to be or you would be setting a code.

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Sunday, May 8th, 2011 AT 12:46 AM
  • Tiny
  • Bcmullen95
  • MEMBER

Setting what code?

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Sunday, May 8th, 2011 AT 12:46 AM

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