Rep Power: 0

i was having some problems with the rpm's on my 01 ex bouncing every now and then.

the mechanic gave me an estimate of around $800 CAN to replace 2 O2 sensors, and do some tune up work (clean throttle body, change oil, clean in jectors, replace plugs...)

the codes that came up were P0420, P0302, 90303, 90304, 90300.
I Know what the codes mean, but i dont understand how they are related to my O2 sensors. wouldnt changing the plugs, and doing the cleaning be enough? they wanted to replace BOTH O2 sensors... and i didnt think that was necessary. replace it when it's broken was my thinking!

 
Rep Power: 452

your mechanic is just parts shooting. All that work listed is basic tune up work. First off I would choose a better mechanic. Once that can diagnose drivability issues. You need to diagnose by the codes. Clear all the codes, drive the car around and see if any come back. More then likely one of those codes are causiing other codes to come up.

Just by looking at what you have, looks like a misfire on cylinder 2. and that is effecting the reading from the o2 sensor. It is also possible that the converter was damaged by the misfire as well as the sensor.

But again clear the codes and see if any come back.