1997 Toyota Avelon Xls-Check enginee light is on

snipped-for-privacy@gmail.com wrote in news:4d2fb03f-fe50-4e2a-bac1- snipped-for-privacy@d21g2000prf.googlegroups.com:

You can drive the car just fine without damage, so don't worry about that.

The worst part is you will likely fail an emissions test with this problem, if you have an emissions test in your area.

The code means the oxygen sensor's internal heater has probably failed. The sensor itself is fine.

Normally the only way to fix this is to replace the oxygen sensor. Guess about $300 for the job.

Also, with the Check Engine light on all the time, you won't know if there any other codes than the P0135, so you'd have to keep gettng the codes read to make sure there nothing new had surfaced.

If the heater circuit malfunctions then the computer stays in open loop. As such it won't be able to properly adjust fuel mixture. It's not good for your catalytic converter in the long run or fuel consumption. Not to mention you won't pass some states' inspections if the check engine light is on. I'd recommend changing it out with a Bosch oxygen sensor. The Zone's got good prices. Calif versions are expensive, like $200 or so; otherwise it's as little as $75 for an excellent planar type sensor. The zone should be able to provide printed instructions, that's supposed to be a new service.

If you are mechanically inclined or have friends who are, Autozone will lend you sensor sockets (free with deposit).

snipped-for-privacy@hotmail.com wrote in news:4a65709e-6b3c-4ba0-9751- snipped-for-privacy@s8g2000prg.googlegroups.com:

As long as the ECM receives a valid signal from the oxygen sensor's element, it will stay in closed loop regardless if the heater is working or not.

The heater is not the only thing keeping the sensor heated up, it's just insurance in case exhaust temps drop below optimum. Plus it brings the sensor up to temp on startup more quickly than if exhaust heat were the only heat source.

Thanks Everybody ...check engine light is yesterday night is off. After 20 miles drive now on again check engine light.

Thank you very much.

Actually, Toyota ECM will go into open loop if the heater circuit is inoperative (see link below). So will GM and Ford vehicles from what I can google. The sensor may not be bad enough to trip P0125, but it's already bad.

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