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Friends,

After picking up my 2005 GS on Friday an putting 150 miles on it my check engine light came on. I reviewed several threads (thank you) and bought a code reader today. It showed a Warm Up Catalyst Efficiency Below Threshold reading. I cleared it and it has not come back on as of yet.

I assume it is because it was bitterly cold the past few days, highs in the low 20's.

Did I assume correct or should I be worried about the Cat? The car has 3,000 miles on it.

thanks
 

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(in case this wasn't solved in the past)

P0421

Warm Up Catalyst Efficiency Below Threshold (Bank 1)

- Catalytic converter is not functioning up to specs
- Oxygen sensors is not functioning up to specs
- Sparkplug problem (not sure about this...)

Clear the code and if it comes back again, you have a problem :)
 

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Is there an easy way for a non technical person to look for those sensors and to see if they have come loose?
 

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Those are the front sensors, part #9 is the back sensors, the P0421 code can be triggered when the from and back sensors don't match the specifications (back sensors should monitor "cleaner" output from the cat converter than the front sensor). Please correct me if i'm wrong.

I'm not sure if its possible to check them without lifting the car in the garage...
 

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Those are the front sensors, part #9 is the back sensors, the P0421 code can be triggered when the from and back sensors don't match the specifications (back sensors should monitor "cleaner" output from the cat converter than the front sensor). Please correct me if i'm wrong.

I'm not sure if its possible to check them without lifting the car in the garage...
Grab a 22mm long open end wrench, jack up the car up front crawl under and tighten them up. there are four two on each side. righty tighty lefty loosy : )
 
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