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'97 CAMRY 4 CYL: OBDII code P0420

My CEL was on for about a year due to this P0420 code (Google "oparr P0420"). The code would return around 10-30 miles after clearing it. Doubted anything was wrong with catalytic converters (California model). Changed the downstream sensor to no avail around 9 months ago, it had seen over 140,000 miles so it was probably due for changing anyway. Upstream sensor had to be changed 20,000 miles earlier.

DMV inspection was due this month (Feb 2009) so out of desperation I tried something that someone recommended for the same issue....Sprayed about a half tin of Berryman's B-12 (same thing used to clean the IAC valve) at the intake while revving the engine. This brought up just about every emmissions code in the book (misfire, O2 sensor, mixture too rich etc.). Also, changed the air filter and added some "snake oil" to the fuel tank.

Well, after clearing codes and over 500 miles later, the CEL light remains off and no traces of any codes. It passed the DMV inspection on Feb 21. I'm now a firm believer in "snake oil" fuel system cleaners for aging cars.

Reply to
oparr
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Besides the problematic (Denso made) oxygen sensors on these cars, you also need to make sure the engine is properly tuned -- for example, timing, spark plugs, fuel filter, valve clearances, etc.

Sounds like in your case possible carbon build up over the years solved by Berryman's were contributing factors.

These engines use multi-port injection, which means fuel is injected into groups of cylinders and sits around the intake valves for a while between cycles. (So I wonder if valve deposits and related rich drivability problems were issues??)

But at least all is f> My CEL was on for about a year due to this P0420 code (Google "oparr

Reply to
johngdole

I'd use Bosch's planar type oxygen sensor, if available for the application, over a cheap heated-thimble type.

Bosch planar type:

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"Lazy oxygen sensors can distort the data and confuse the PCM. So if the sensors are suspect, or their age can=92t be determined, replace them. Even if you have to replace more than one, the cost to the customer will most likely be less than the cost of a converter. The precat oxygen sensor is also responsible for fuel calibration. This promotes maximum engine efficiency, which also allows the catalyst to perform at its peak efficiency. If the engine is not performing as designed, catalyst efficiency will also suffer. "

Reply to
johngdole

Seems like it. Going to order some B12 fuel system clean-up and add it to the gas tank every 3000 miles as they recommend.

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Reply to
oparr

I also heard about Auto-RX. I've never used it, so I don't know how well it works. But sounds like it can help clean up the lube system's varnishes. See:

"Auto-Rx Cleans Engine Internals, Transmissions, Power Steering, Differentials, Seal Leaks and also takes care of Sludge/Heavy Oil Burning."

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Reply to
johngdole

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