check engine light from coolant overflow

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  #1  
Old 11-21-04, 09:04 PM
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check engine light from coolant overflow

Hello,

I have a 1997 Ford Taurus and I am having a problem with the check engine light. It happened when I put too much coolant in the overflow tank. When I was driving, I noticed the light come on, so I pulled over and carefully unscrewed the overflow tank cap. Coolant came flowing out. When it subsided, the overflow tank went practically empty; I think whatever coolant was left in the overflow tank went back to the radiator. So, I added some more coolant since it was below the minimum (and this time being careful not to go past maximum). Now, everything is working fine. The engine isn't getting to hot and the coolant in the overflow tank is normal. However, the engine light stays on. I disconnected the battery to try to get the computer to reset itself but after a few seconds of driving, it came back on. Any ideas as to what could cause this and if I should have it checked out?

Thanks,
daufoi
 
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  #2  
Old 11-22-04, 04:27 AM
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A 1997 vehicle will be OBD-II; you can't reset the light without a scanner. Try going to your local AutoZone, if there is one in your area. They will read your code and reset the light. Post back here with the code for further advice. Overfilling the coolant tank will NOT cause a check engine light.
 
  #3  
Old 11-22-04, 11:21 AM
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Thanks for the advice. I went to autozone and got a code of P1131. The unit said "fuel air metering system" (not sure if that's exact). Looked it up on the net and it says "P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1". The mechanic said it could just be the air filter but since I haven't been having performance problems that it is probably something minor. I did clean out the air filter (I found a bee in it) but it didn't make the engine light go away. What do you think?


* I was reading more about what the HO2S does and what it means to indicate "lean" (that there are high traces of oxygen in the exhaust stream) and maybe someone can tell me if this line of reasoning makes sense: If there was too much coolant in the system, there was steam going through the engine, ending up in the exhaust stream. The sensor picks up on the oxygen from the steam and turns on the engine light. If this is correct, will the engine light go off as the steam is completely removed from the system? Or, is there something I can do to get the steam out? How would you handle the situation?
 

Last edited by daufoi; 11-22-04 at 12:49 PM.
  #4  
Old 11-22-04, 05:10 PM
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No, forget the coolant idea. That's not the problem. The code indicates the car is running too lean. Ther most common cause for that is a vacuum leak but many other things can cause that. First you have to make sure the sensor is accurate by reading the voltage with a DVOM while you artificially enrich it and watch for the voltage change. The voltage range is from 0 volts to 1 volt. anything over .500v is considered rich, under .500v is considered lean.
 
  #5  
Old 11-23-04, 05:08 PM
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Well it went away after less than a day's driving and hasn't come back since then. I'm not going to worry about it for now since the car runs well.
 
  #6  
Old 11-29-04, 04:41 AM
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Think I would find a new mechanic, too. A dirty air filter causing an O2 sensor code?

Desi???
 
  #7  
Old 12-07-04, 04:34 AM
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Thumbs up Air Filter ??? Engine Light ????

CALM DOWN! The_Tow_Guy, I Have seen a DIRTY AIR FILTER be the cause of a LEAN CODE. What happens when dirt or any foreign object gets hung on the HOT and COLD wires of the MASS AIR FLOW SENSOR? This could be the reason the CHECK ENGINE LIGHT went out. They checked the air filter and in doing so dislodge the object?? Just a thought!
 
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