I have a 1999 Honda Civic Si, 75K miles. The engine light came on and, after testing, the mechanic replaced the #1 (before catalytic converter) oxygen sensor. After 2 weeks, engine light came back on. He replaced sensor again. Now the engine light is on for a third time. A different mechanic tested it and said it was the #1 sensor and not an exhaust problem. He wants to try replacing the fuel filter. Any ideas on what the problem could be? Thanks!
Ask your mechanic what testing procedures he is using to determine oxygen sensor failure.
What code is leading the second mechanic to want to replace the fuel filter? (a lean code?)
I don’t understand what you mean when you say “A different mechanic tested it and said it was the #1 sensor and not a exaust problem”
By #1 sensor you mean oxygen sensor? It seems you have a different mechanic that says the sensor is bad but wants to replace the fuel filter,what do you mean “not a exaust problem”?
I think it might be the catalytlc converter. Basically, the Oxygen sensors ensure your catalytic converter is doing its job, among other things. So if your computer doesn’t like the readings it is getting from the Oxygen sensors, I would not have assumed the sensors were necessarily at fault. You might also have something like a bad air flow sensor, a leaky fuel injector, or a cylinder that isn’t firing.
It is time to stop throwing money at either of these mechanics and go to one who has a better idea of what he is doing. You might try the Honda dealerships in your area if you haven’t already.