oxygen sensor

[Stellapr]

My check engine light came on two days before I had an appt to get car inspected. Mechanic said it was "oxygen sensor slow response." He said since there was a response left he would just clean and charged me $14 for the cleaner. So far a month later the check engine light has stayed off. My 2004 Corolla only has 30,000 miles on it so don't understand why the oxygen sensor would be having problems. Boy the car really runs great and quieter since he cleaned it. He said it would cost $90 to replace sensor. He did say alot of city driving can cause this which I do.

Diane

[fishexpo101]

O2 sensors do have a finite lifespan, but even 30K miles is considered pretty short, regardless if it is was all city driving or not. Assuming that no modifications have been done to the engine, no oil consumption.

Also assuming that the code was stored was P0133 - though O2 sensors in general cannot be "cleaned". In fact, even if you found a solvent that didn't foul the sensor directly, the action of cleaning would also carry foreign material from outside the sensor body to the sensor itself. I'm interested in what "cleaner" was used in this case and how it was applied to the O2 sensor. Atleast he only charged you $14.

Wondering if you had a dirty MAF sensor that triggered the initial DTC (Diagnostic Trouble Code). That and dirty throttle bodies can cause all sorts of issues, especially around this mileage. Another common source to cause this code to come up is an exhaust leak. The union between the exhaust manifold and front pipe can leak exhaust, given that it is designed to be flexible. Even a small leak can cause the car to "read" an incorrect amount of oxygen in the exhaust stream.

Has the fuel economy changed appreciably since you had the car, i.e. MPG have been dropping over time?
Has the mechanic backprobed the O2 sensor to verify that it is working as spec'd?

Possible that you have a bad O2 sensor, it happens. If you do decide to replace it, make sure it is a Denso unit - too often we see the car run poorly with a universal or other aftermarket O2 sensor. Doesn't mean that aftermarket are poor choices, just means that the engine is picky about the sensor - some run Bosch or other aftermarket with zero problems - others end up running through several aftermarket ones until they install a Denso unit to get the car to run properly.