Hi,
During the fall my 99 SE started occasionally skipping while at Idle, otherwise the car ran fine. A month or so ago I read the computer and got 0304, Knock sensor and 0510, downstream O2 sensor high voltage, then reset the computer to see if the codes came back. The knock sensor code did. A week ago I changed the plugs to the Bosch Platinum 4+ and the engine started hesitating real bad on accelaration and made a popping noise while it still thumps at idle. I also got a new code, #5misfire. I put a new knock sensor in last night, reset the codes and drove today. Still the same thump at idle but the engine seems a little smoother, maybe the knock sensor helped a bit. Tonight I read the codes again and low and behold it says the 0304, knock sensor and the previous 02 sensor code. I reset the computer, turned the ignition on and the knock sensor code is still there. I cant figure whats up. Maybe coil pack on #5? but why would I still get a knock sensor code after resetting the computer and only turning the ignition on (Wiring?) and the still bothersome hesitation on acceleration. Plugs are new but I read some have problems with bosch. Maybe the #5 coil causing something. Funny thing, only got the bad acceleration after changing the plugs. Anyone have any ideas?

Jon

 

I think you have multiple issues.

One, I've read a bad o2 sensor can trigger a knock sensor code. So I woulda replaced the o2 sensor first, then see if the knock sensor clears up.

About the knock sensor coming up immediately after you reset the ECM... but if you turned the car on, then checked for codes afterwards...well then maybe there is a wiring issue.

Maybe that #5 misfire is due to a weak coil pack that you talked about (skipping/hiccupping at idle in the fall). Maybe those bosch plats exposed the weak coil pack, since they are not recommended.

Which gives me an idea. Maybe I should try a set of autolites, and try and expose which coil pack on my car is giving me hiccuping at idle.