Camry 2000 P0420 code after head replacement

BORISP

MEMBER
2000 TOYOTA CAMRY
4 CYL
FWD
AUTOMATIC
95,000 MILES

Hello,
I have a 2000 camry with 4 cyl engine and CA emissions. The car overheated due to broken water pump, and I replaced the cylinder head (in addition to pump and timing belt). The cylinder head was a rebuilt from a machine shop. Since the replacement the car starts and runs fine, but I got a p0420 code. I know that it means the front catalytic converter, but I don't know why it came up right after the cylinder head replacement. I am curious if the machinist may have cut the head down too much and the increased compression ratio is causing increased emissions, triggering the code. I don't want to spend the money on new converter if the problem is in the cylinder head. I also tried measuring the compression, but it is impossible to pick up a small difference in cylinder compression using a compression gauge. Also, I used a standard multy-layer steel head gasket from FelPro, if that helps you.

4 Replies

RASMATAZ

MECHANIC
75,992 POSTS

P0420 could be the converter itsef, oxygen sensor, too rich of mixture, bad plugs and valves and cylinders burning oil contaminating the catalsyt etc-

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Thursday, August 25th, 2011 AT 3:21 AM

BORISP

MEMBER
2 POSTS

Let me clarify. I replaced both the front and rear O2 sensors with new Denso units, as these were the OEMs. I also put in brand new spark plugs, also OEM. The car is not burning any oil (I have close to 10k on it since the repair and the oil does not go down on the dipstick). I think that the mixture is fine as there is no reason for it to change and I still get 30-32mpg on the highway. This is why I am puzzled and the only thing that I could come up with was increased compression ratio since that may increase emissions, but I don't know.