QuestionI have a 1998 Toyota Avalon 6 cyl, Auto trans with 95780 miles. The vehical failed it's CT Emissions Test. Diagnotic Trouble codes P0125, P1150 and P1155. The check engine light was reset by my mechanic intially a month ago and within a 25 miles the light went back on. After the next gas up the light went off for a few miles and then came on and stayed on. These codes were the result of the emissions test.
AnswerBill,
I'll need a little more information.
Does the car start, idle, and drive correctly?
At what miles and date was the car tuned up last?(plugs,air filter).
The emissions control system on a vehicle is basically a bunch
of sensors that constantly send signals back to the ECM/PCM (computer). When the scanner picks up codes its really not that
sophisticated to understand what's going on. For a simple example
say; spark plugs are really worn so that the gap is 90 thousands and should be 35 thousands (I've seen this happen) the computer says the source is the 02 sensor which measures the air/fuel mixture in the exhaust burn-off which means the output exhaust is off. This DOESN'T mean the sensor is bad! There is something that is causing the
sensor to send a negative signal back. In addition, 02 or MAF
sensors get dirty over time just like anything else in the world.
When they are dirty, they won't function properly.
I assume you've checked the gas cap, that vehicle should have
3 oxygen(02) sensors. They probably need a good cleaning, NOT
replacing.
Tim
