O2 sensor

I drive a 1997 toyota camry. The check engine light has been coming on. According to my mechanic it is because of a bad o2 sensor. I have replaced the sensor 4 times. The check engine light just comes on a few days later. I am supposed to take an 800 mile road trip (400 miles both ways). Would this be okay to do? I have to believe there is some way to fix the problem. Any suggestions. Thanks!!


I hope you haven’t paid for the sensor 4 times?

Can you post the exact fault code, please

My dad has. I decided to take the issue into my own hands because he will not listen to anyone besides the single mechanic he sends all of his cars to. The code is p0133.

Also i have been reading that toyotas are sensitive to o2 sensors and require factory parts. Is this true?



I couldn’t find any Toyota bulletins for that code that apply to your car, but I found this.


Are you sure that the upstream oxygen sensor has been replaced, versus the downstream sensor?

And was a Toyota part installed?

Or at least a Denso sensor?

I have personally fixed vehicles with that exact code that were caused by exhaust leaks upstream of the sensor.

Here’s my advice:

Put the car on 4 jackstands

Open the hood

Start the engine

Crawl underneath and listen/feel for any obvious exhaust leaks in front of the upstream sensor

Visually confirm that the sensor harness doesn’t have any rat damage, and that everything is plugged in all the way.

Listen/feel for any obvious vacuum leaks in the engine compartment

On a 16 year old car a leak in the original exhaust system is almost a given.

You probably already understand this, but a code for the O2 sensor doesn’t necessarily mean there is anything wrong with the sensor. It is common for folks to replace the sensor without doing any checking, b/c the sensor is relatively inexpensive and easy to replace. But the problem is that the replacement sensor is probably not as good quality as the original. Do you have the original sensor back in the car now?

A O2 sensor problem just means the ECM isn’t able to get the expected readings from the sensor. Could be the sensor, sure, but it could also be a fuel/air mixture problem, an exhaust leak, or if a heated sensor heated sensor, the circuit is faulty, a fuse is blown or it has become disconnected.

My inclination here is to check for a cracked or loose exhaust manifold. Esp if this is the 4-banger version of the Camry.