Toyota Camry error PO420 exhaust sensor problems

These codes are usually just indicators that a problem exists but often not specific enough to go replacing parts without further diagnostics.

Was there only the one code? That would be unusual.

Some things to check would be 1) electrical connections to the oxygen sensors, 2)leaks at manifold gaskets, 3) proper air/fuel mixture (need an exhaust gas anylizer) 4) any other codes.

Try cleaning the contacts on the intake "MAP" sensor (female and Male) and verify that

they are making good contact. Then check the O2 sensor contacts and clean those as

well. GL

Clean out the hose/tubing that goes to the sensor.

Code PO420 is a OBD 2 Generic Code which is not manufacturer specific and applies to all makes and models including imports .

The code PO420 is defined as ; Catalyst System Efficiency Below Threshold ( Bank 1)

I would check for leaks in the exhaust system including the manifold , bad connections on the Oxy. Sensors , leaking Oxy. Sensor threads, cracked or faulty Cat. Converter.

Sounds like one of the replacement parts you had installed is causing the grief.

Question : Why did you have to replace the manifold and Cat. Converter previously ?

I had the front exhaust(integral Catalytic converter) system replaced by Speedy last fall 2008 .I went to Speedy because the parts and labour were about $500 cheaper than the parts alone from Toyota.. It took about 6 months before the PO420 error came up. I reset it and it would take about a week before it came back. The estimate from Toyota just to diagnose the problem was more expensive than the cost of the sensors I replaced (Bosch and NTK). The cost of original Toyota parts are too high (one sensor is more than the cost of both units I bought through NAPA).

I will take all the tips in mind and inspect things more closely.

Tks folks.

Most parts sold by NAPA will meet or exceed OEM specifications.

man i hav the same problem except mine smokes every morning when i start it any help on that

After checking some of the other reply's make sure the sensors are getting power. They heat up electrically before the engine warms up.

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Check the gas cap. My wifes old Grand Am threw this code several times and it was always a loose gas cap. If it is loose it will take several "good" trips before the light goes out if you don't have a way to reset it.

Shawn

Hello

I can feel your pain as my wife has the same problem with her 2000 Camry. She also had her catalytic converter replaced after an accident several years ago. My feeling is that the replacement catalytic converter was an after market one and after so many miles it does not remove the contaminants, triggering the PO420.

I would ask the question, "Was original equipment used when replacing the cat"?

We have not found a course of action yet and are still searching for a solution other than replacing the whole cat.

Let me know how you make out.

Hello

This is an update to the previous post and should help some people with the same problem. It wasn't the Cat!

This is usually a oxygen sensor and the Camry has 2 of them. If you get this code try removing the sensor and using a wire brush to remove the carbon scale build up. Clean 1 at a time and use a OBDII code reader to clear the code. If the same sensor comes back on replace it, if not clean the other and repeat process.

I also have a Volvo and cleaning the sensor and clearing the code, the error has not come back.

The sensors are also very easy to remove by unscrewing them using an adjustable wrench. Cut the wire ties leading up to them, because as you unscrew the sensor the wire will twist. If you don't cut the ties the wire could break under stress.

Good luck.

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