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Discussion Starter #1
Well After replacing the clutch in my zx3 the engine light finally came off for the first time since I owned the car, I was quite happy but just the other day the check engine light came on and I went and got it checked out here is what the codes say tell me what you guys think.

Definition
aaaCatalyst efficiency low-bank 1
Explanation
aaThe oxygen sensors monitor the catalytic converterss
aaability to store oxygen
Probably cause
aa1.-Catalytic converter defective (failure possibly due to # 2,3, or 4)
aaa2.- Engine misfire or running condition
aa3.- large vacuum leak
aa4.- Engine oil leakage into exhaust-valve guide seals, piston rings



The guy at autozone told me this could be effecting my gas millage which I noticed was a little on the short side.. about 22-25mpg

What are you guys thoughts on this I have no clue where to begin fixing the issue
 

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bank 1 sensor 1 or bank 1 sensor 2? if its number 2 it shouldn't affect gas mileage. check the connection (could have forgot to reconnect after the install)

it probably turned off because the battery needs to be disconnected, so then the computer started to re-check everything and the CEL is back.

worst case you need a cat and a 02 sensor. i would check everything out, then change the 02 (or just go to a wreckers and pull a cat with an 02)
 

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DTC P0606
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Was it the DTC code below? If it happened right after your clutch work, I'd bet the rear O2 sensor wasn't connected properly or the wiring was damaged as Mike_Mac suggested. Did you ever get the "original" DTC code read?

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
Indicates Bank 1 catalyst system efficiency is below the acceptable threshold
Use of leaded fuel
Damaged HO2S
Malfunctioning ECT
High fuel pressure
Damaged exhaust manifold
Damaged catalytic converter
Oil contamination
Cylinder misfiring
Downstream HO2S wires improperly connected
Damaged exhaust system pipe
Damaged muffler/tailpipe assembly
Retarded spark timing
Compare HO2S upstream and downstream switch rate and amplitude. Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which makes the switching frequency of the downstream HO2S very slow and reduces the amplitude of those switches as compared to the upstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal begins to switch more rapidly with increase amplitude, approaching the switching rate and amplitude of the upstream HO2S. Once beyond an acceptable limit the DTC is set.
 

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cat efficancy only come from rear o2 it should be the P0420 as listed code. Check for exhaust leak between 02's. Damaged wires should not throw this code also getting the o2 full of oil or such can cause this code. I would test the rear o2 or even replace it before the cat. unless you damaged the cat diring clutch install. (banged it good)
 

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check wiring check scan tool for activity of o2.
 
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