Does my 1998 Camry need a new oxygen sensor?

My mechanic tested the o2 sensor on something like an engine anaylzer with tailpipe sensor, any mechanic that does not test something is a hack.

The engine management computer constantly tests the O2 sensor by adjusting the engines mixture slightly off stoichemetric (14.7:1 air:fuel ratio) in both directions (rich and then lean), while simultaneously looking for the correct correlating signal from the O2 sensor. If the signal from the sensor remains unchanged, then the computer will light the check-engine lamp.

Its possible, the sensor was temporarily unserviceable due to an intermittant wiring fault, or some exhaust deposit on the sensor.

To be sure, I'd ak the mechanic if he has done something to the car to stop the alarm,..other wise all could now be well.

If your economu is normal, that's another indicator the O2 sensor is working.

Jason

If it isn't working properly you should change it, but I would try some Red Line complete fuel system cleaner first. Can be used continuously and is reported to clean emission control components. O2 sensor in my '94 still tests good - although it is a slightly different design than yours, I believe those sensors tend to fail from carbon accumulation so would try the cleaner - but only the Red Line was rigorously tested and approved by BMW. Others have solvents, or raise combustion temperatures. Just my opinon, but have been very pleased. If you're intersted, their web site has an extensive technical data section.

True, the only way to test an oxygen sensor is with smog equipment or in a lab while looking at the waveforms, but nevertheless a difficult thing to do. So if it's not giving you MIL codes and your mileage is not dropping then you may want to wait on it.

There are many posts lately on failing Camry oxygen sensors. So I'll say stay away from Denso ones. If you need to replace it, get a Bosch unit. I think Densos are el-cheapo units that fail early, their website still thinks today's engines are dumping lead and coolant onto the sensors.

US made Toyotas are more likely to get a Bosch unit than Densor or NTK.