Hopefully someone has some experience they can share with me on this one. And let's please not let this turn into a brand-loyalty war.

I have a 2001 Civic EX. VTEC motor. This car has been 100% reliable until now, and has had *all* the factory recommended maintenance done to it (by me). 117k miles. New timing belt at 105k. This is why it didn't take me very long to replace the sensor - I knew right where the little bugger lives. But this latest problem has me stumped.

A few nights ago, the CEL came on. Car ran fine, Leilani took it to work the next day. On the way to work, fine. When she tried to drive it home, it didn't want to start, finally did, idled like crap, ran rough, and stalled repeatedly. She brought it home and I bought an OBD-II code reader the next day (finally, an excuse to get one!). The code was for the camshaft position sensor out of range/not responding. $45 part from the dealer, it took me about 3 hours to replace it. Test drive it, runs fine, no codes.

Leilani takes it for some errands. Calls me later, tells me it's acting up again. Runs rough, stalls, etc.

Hook it back up to the reader, P0420 - Catalyst System Efficiency Below Threshold.

Great - what does that mean? A new cat, or a bad O2 sensor? I clear the codes and take it for a ride, as I still haven't had it act up on me. The car starts OK, but immediately runs like crap. I take it to the end of the street and limp back. Put it on the reader again, P0301 - Cylinder 1 Misfire. No P0420 code this time.

I took out the spark plug and the coil module, and both look fine. I made sure the connections were tight and there was no corrosion. Put it back together, it runs fine. I clear the codes and take it for a 30 minute drive. No problems whatsoever.

Put the reader on it for kicks, and P0301 comes up again. I *thought* it missed once, but I was running it pretty hard and I thought it might have been the VTEC kicking in, which feels somewhat like a miss.

I'm letting it cool down and I'm going to drive it again later after clearing the codes. If I get the misfire code, I'm going to swap coil modules between cylinders and see if the code follows the module around.

Right now, I'm thinking that I have an intermittent coil module, which was causing raw fuel to get dumped into the exhaust, which was throwing off the efficiency of the cat. I didn't get the misfire code and the cat code at the same time, but it seems reasonable anyway.

However, this doesn't explain the camshaft sensor code, and I think it's odd that sensor would fail anyway as it's just a magnet wrapped in copper wire and encased in plastic. No moving parts, nothing to fail. The connector looked fine, no corrosion, no exposed wires or anything else.

Am I missing anything? Does anybody have an idea what might be happening with this car?

Thanks!!!!

 

I don`t know if this helps or not but a friend of mine was working on a small car showing cam position sensor fault. He replaced the sensor, made no difference. On closer inspection he found that the timing chain was worn (I know yours is a belt). He replaced that and cleared code and perfect. My point is could your Civic have jumped a tooth on the belt or could the variable timing be faulty, throwing the cam position sensor code? Good luck with it.

 

Ahh the CEL code, one thing I despise about hondas, including my own!

Regarding your 0420 code, i remember reading one time that this can occasionaly be caused by a crack in the exhaust, it might be something to check.
Im sure you checked the net but heres a good link on that code. Troubleshooting P0420 Catalyst Code


The cylinder mis fire can be easy to fix, change the plugs. But it could be the injectors, and I have heard of the timing belt jumping also. Id check the plugs then the injectors, start small.

 

Andy,
I had an intermittent IAC issue with my daughters '02 civic a few months back. I never got a chance to pull codes before I took it to the dealer. But the car did act the way that you describe. Check all vac lines around the intake.