juror

This is a follow-on to a thread from last week. I deferred ordering a new LAF until after taking the car back to Autozone and having them confirm the code. At $100, I want to be sure I saw the code right.

Today when I jumped in the car and started it, the MIL didn't come on. I took the car to Autozone anyway, and they were able to scan it and see that there was a stored P0134.

As part of the suggested diagnosis, I unhooked the connector at the LAF to check the contacts, which were clean. I cleaned them with Deoxit just for grins and hooked the sensor back up. The MIL remained on after that.

At this point, it seems like there are a couple possibilities:
1) Disconnecting, cleaning the contacts, and reconnecting the LAF sensor restored the connection but the ECU leaves the MIL on for a certain number of cycles/miles.
2) Very intermittent wiring issue. The bumps in Boston gave a compensatory jostle to the rattles we incurred driving around VT and NH last weekend?
3) Flaky but mostly good sensor?
4) Something to do with our niece being around? We had the same problem last fall when she was born. The car hadn't been around her again until last weekend because we'd taken my Impreza up to NH the several times we visited this winter. Can my partner's Civic just not handle the cuteness?

Anybody want to weigh in on the odds of each of these? All joking aside, the MIL did come on last September and then went off again before I had a chance to deal with it. I'm pretty sure it was a sensor related code, but I don't know if it was for the same sensor.

At this point, I'm content to wait until the problem reoccurs. If it does, I'd like to how to best go about diagnosing the issue for real.

The car in question is a 2005 EX, in case you don't want to go chasing through the other (short) thread.

GolNat

iTrader: (7)

The sensor may be dirty or on its way out.

In order to reset the ECU you have to disconnect the battery for a couple minutes.

juror

Should we just sit on it until it becomes a reproducible problem then? At the moment it's wildly intermittent (if it's even the same problem as we had in September).

Are we going to hurt anything (e.g. the catalytic converter) if we keep running into this?

Thanks for the help!

Reverb2005

The sensor has a very fine range of temperatures where it works "properly". The sensor is only heated if the temperature of the sensor is less than 750 degC.

Your sensor is producing a fault related to the heated component. So basically, you may only notice the fault when the sensor is trying to heat itself to the proper temperature.

In short, yes, you can damage the cat if you use a faulty sensor. If you are running very rich (i.e., more fuel than the air can burn) the fuel will "burn" or oxidize in the cat, which creates heat, a lot of heat. This heat will degrade the components in the cat and destroy it over time.

Now, I can't say that it WILL ruin your cat, only that it COULD ruin your cat. Really, the best thing to do is just replace it. It is usually only a one-time replacement, depending on how long you own the car. If it were the O2 sensor, I would say it is not a big deal, but the A/F sensor is substantially more important when it comes to the efficient operation of your engine.

Also, no need to pull the wires off the battery to reset the ECU, just pull fuse #6 (under the hood) for about 10 seconds and re-insert. This way you don't have to re-program your radio, etc.

juror

Wow, thanks for the great answer Reverb! I was afraid that was going to be the case :-( Off to Amazon I go!