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Service engine light

B

buck

New member
My service engine light came on. Went to AutoZone, after they tested it, it came out "catalyst efficiency low-bank 1" Then he tried to sell me a new catalytic converter! I actually read the slip of paper he printed up (and let me keep). I think I'll start small with a tune up, even though the guy at the Zone said I didn't need one. It has 103 K miles and original plugs. then on to trying to find a vacuum leak. I already looked for holes in the exhaust and didn't find any. Wish me luck

2003 Grand Prix GT Limited Edition.
 


Depending on what code it was I would say may be time to add a new upstream O2 sensor (the one on the rear manifold) to your list of tune up items. It would work to your benefit as well since that O2 is in the way of #6 cylinders' plugwire boot anyway.
 
It just dawned on me that about a week ago my son ran out of gas in the car. He used a gas can that use to mix two cycle engine oil in. It had about a gallon of 50/50 mix. Then I filled the tank later. My thought is that mabeye the oil gas mix screwed up the 02 sensor. (making the car think there was an oil leak inside the engine). any thoughts?
 
Would this be the ever so popular P0420?


[h=2]Causes[/h]A code P0420 may mean that one or more of the following has happened:
  • Leaded fuel was used where unleaded was called for
  • An oxygen sensor is not reading (functioning) properly
  • The engine coolant temperature sensor is not working properly
  • Damaged or leaking exhaust manifold / catalytic converter / exhaust pipe
  • Retarded spark timing
  • The oxygen sensors in front and behind the converter are reporting too similar of readings
[h=2]Possible Solutions[/h]Some suggested steps for troubleshooting a P0420 error code include:
  • Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
  • Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
  • Inspect the downstream heated oxygen sensor (HO2), replace if necessary
 
buck said:
It just dawned on me that about a week ago my son ran out of gas in the car. He used a gas can that use to mix two cycle engine oil in. It had about a gallon of 50/50 mix. Then I filled the tank later. My thought is that mabeye the oil gas mix screwed up the 02 sensor. (making the car think there was an oil leak inside the engine). any thoughts?
Click to expand...
You run your 2 cycles 1 to 1??? Go through plugs much?
 


Has your cat been replaced? If an aftermarket converter was used, it may be the problem. I know of several people that have had issues with the P0420 code after a new cat was installed, they simply do not do a good enough job and the code is thrown.
 
O.K. a little exageration. I follow the manufacturers specs. My question is would mixed gas hurt a car
 
Has your cat been replaced? If an aftermarket converter was used, it may be the problem. I know of several people that have had issues with the P0420 code after a new cat was installed, they simply do not do a good enough job and the code is thrown.
Click to expand...

this just happened to me. what is there to do?
 


is that all you can do? i dont want to spend all that money to get it tuned out. and its going to be a while before i drop my pulley and get a tune for that
 
I have a high flow cat, and the code was removed. You can just let it be until you do the pulley drop and tune.
 
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