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
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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
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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
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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
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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
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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
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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
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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
Tiny
BCMULLEN95
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What code are you referring to?

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Sunday, May 8th, 2011 AT 12:47 AM
Tiny
WRENCHTECH
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Your computer is not picking up on any problems on bank 2 so there is no reason to be questioning anything there.

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Tuesday, May 10th, 2011 AT 8:34 PM
Tiny
BCMULLEN95
  • MEMBER

I understand what the code is stating, but as researched other forums one stated that the code could come from the O2 sensor on bank 1 and bank 2 having the same reading. As I was checking the functionality of both sensors I notice the O2 sensors on bank 2 not flucuating and it raised a question as to whether or not the is common for this type of a car. My other car have fluctuating readings on the O2 sensor on bank 2. Can you explain to me why the O2 sensor on bank 2 in not changing it voltage reading, and staying at a constant 1.25. Thank you

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Friday, May 20th, 2011 AT 12:58 AM
Tiny
WRENCHTECH
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I suspect it is a problem with your code reader. If it was really happening, it would be setting a code.

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Friday, May 20th, 2011 AT 1:02 AM
Tiny
BCMULLEN95
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As doing further research is it possible the O2 sensor has malfuction setting this particular code? In one site these are the possible reasons
1.) The catalyst in the catalytic converter is cracked, clogged, or otherwise damaged.
2.) The secondary O2 sensor is malfunctioning.
3.) There is an exhaust leak.
4.) The computer unit is faulty

Based on this the O2 sensor is not working pronperly correct?

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Friday, May 20th, 2011 AT 1:10 AM
Tiny
WRENCHTECH
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You keep looking for a problem on the side of the car where the computer is not finding a problem and I'm just not going down that road.

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Friday, May 20th, 2011 AT 1:31 AM
Tiny
BCMULLEN95
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So what your saying is I paid you to not help me!

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Friday, May 20th, 2011 AT 2:42 AM
Tiny
WRENCHTECH
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This is a 4 cylinder car. It shouldn't even have a bank2. I'm afraid I can't help you.

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Friday, May 20th, 2011 AT 2:46 AM
Tiny
BCMULLEN95
  • MEMBER

So why not state that earlier instead of side stepping the question. I intended on asking why the O2 sensor after the cat is staying at a constant 1.25v and does not change. I appologize for the confusion on my part. The O2 sensor is faulty correct?

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Friday, May 20th, 2011 AT 7:52 AM
Tiny
RASMATAZ
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For better understanding on P0420 Go to this link and read more on it-

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Friday, May 20th, 2011 AT 10:11 AM

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