So here's a quick question with a long story. I have a 2006 GS, that is probably more factory than when it came from the factory. This is my everyday driver as I needed something that could handle the 100 mile/day commute. Anyway CEL came on a couple of years ago, had the codes read and it was supposed to be an O2 sensor (don't know which one, didn't know it had more than one) Have I mentioned that I'm pretty ignorant of new engine technology? My other vehicle is a F-250 diesel so I've been out of the loop for a little while. Anyway I even mentioned this at my dealer and he told me that if I wasn't seeing a fuel milage problem that is was probably just the pre-heater in the sensor, and that was probably what was throwing the code. So like any good moron, I ignored it. So skip a couple of years and we're at the present with 125,000 miles. Took it in last week to have the belts changed and the plugs changed out, and of course to try and get the CEL fixed. When I picked it up they had read the codes and told me it was the O2 sensore, but forgot which one, told me to swing it back by when the light came back on and they would read it again. On my way home I noticed the exhaust seemed to be louder and the pedals had more vibration in them. The car also seemed to be a lot more sporty with much less backpressure noticed when I shifted gears. So my immediate thought was, bet they left something loose on the exhaust when changing everything out. Anyway the CEL came back on the next morning on my way to work, so I took it back by that night, except this time it's throwing PO421 and PO431 codes with no mention of O2 sensors. I had him listen to the motor and he couldn't hear any exhuast leaks, and then I took it to a muffler shop to check the cat(s). They said the main cat checked in speck, but they couldn't check the precats. But they told me that the were all running hot. So at this pioint I am completely lost, and looking for suggestions...any help would be greatly appreciated. And before the obvious is mentioned this is a mechanic that me and my family have used for years, who drives and works on imports and has always done a great job, so I don't think he is pulling any tricks.
Also in summary, the car has no mod's whatsoever, the plugs were replaced with NGK Iridiums and the timing belts and drive belts were all that were replaced. It doesn't run rough at idle and the increase in sound only seems to become evident at around 2000 rpm, increasing up to ~4000 RPM.
Thanks,
Josh
Also in summary, the car has no mod's whatsoever, the plugs were replaced with NGK Iridiums and the timing belts and drive belts were all that were replaced. It doesn't run rough at idle and the increase in sound only seems to become evident at around 2000 rpm, increasing up to ~4000 RPM.
Thanks,
Josh
