Hey guys I have a 90 Civic sedan and it thrown a single flash code on the ECU. I found the thread that lists the codes and a single flash supposedly means that oxygen sensor #1 must be bad or something. Does anybody know where that sensor is? Isn't that one that goes in the side of the exhaust manifold? Any assistance would be greatly appreciated. Thanks.


Modified by dbailey at 9:38 AM 11/7/2007

 

Single flash is code 1.
Code 1 = o2 sensor #1.

 

Oooops! Guess I misread it. Any idea where that is and if it throws that code if it means that the sensor is bad! The check engine light comes on but has always gone off when I turn it off and restart it.

 

You have a bad 02 sensor. I have the same issue. The code will come on when the car when you are engine braking or are steadily pushing the throttle, and will disappear when you restart the car. It's normal. Just replace the 02 sensor

 

Yeap that's exactly what happens. It hasn't been that long since I replaced it though. Hmmm..... What's the consequence of driving it with it bad?

 

I wouldn't do that for a prolonged time. The engine will run rich, meaning there will be too much fuel, which is not all burned off. This is bad for the piston rings.

 

Ugggg. And with an engine that has 175,000 on it and is already knocking I guess I better do it. The light has only come on like twice in the past couple of months. Does that maybe mean that the sensor is starting to go bad or is once the check engine light comes on once, bad is bad?

 

I wouldn't leave it for say, a year, but replace it when it is convenient to do so. There is certainly no rush. I'm going to wire up a 4 wire instead

 

Thanks for the advice! Good luck with the rewire project.

 

The excess fuel actually mixes with your oil. You can tell because at first your oil level may actually rise, but in the long run, it will start burning oil, then maybe the valves, like mine did. I lost #3 cylinder, but I ran it for 40,000 miles like that, those things just keep on running.

 

Not sure why or what causes mine to deposit soot on my rear bumper right around the exhaust pipe. Blowing oil maybe? I do hear a rod knock kind of sound when I start it up but it goes away once eveything swells up when it warms up.

 

Black soot is a sign the engine is burning rich. Blue smoke would be oil burning. I put a non OEM O2 sensor in mine for around $30.00 and have not had any problems. Real easy to replace, get the engine hot, then wait until it cools down a little, then wrench the O2 sensor out.

 

Ah ha! Advance Auto sells a universal one that supposedly you have to splice your connector onto for like $18. Ever heard anything good or bad about the universal ones? Thanks for the info.

 

i've always bought the universal (bosch) ones from autozone

 

This is the one I bought. Splice it, tape it, put some celophane around it and you are good to go.

 

As I recall the last time I replaced that buggar, you have to take that shroud off of the exhauat manifold to be able to get to it. Yes? I know this guy that let me borrow one of those deep well sockets that has the side sliced out of it so you can slip it over the sensor. Any other suggestions on how to get it out without having to take that shroud off of the manny?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dbailey &raquo;</TD></TR><TR><TD CLASS="quote">As I recall the last time I replaced that buggar, you have to take that shroud off of the exhauat manifold to be able to get to it. Yes? I know this guy that let me borrow one of those deep well sockets that has the side sliced out of it so you can slip it over the sensor. Any other suggestions on how to get it out without having to take that shroud off of the manny? </TD></TR></TABLE> its like 3 bolts. Unless its rusted on then you have a problem. I think they are 12mm or something.

 

You should be able to reach around the shroud if you have to, or come up from the bottom. If you are splicing the new one, you can just cut the wire down close to the sensor and use a regular socket. If worst comes to worst, you can remove the radiator for easier access. I bought an O2 socket for around $5.00

 

I looked and it is a really tight fit where the shroud is in relation to the sensor. The socket would have to be a really thin walled one to get between the sensor and shroud. I did get one of the universal ones where you have to splice the wire. Will prolly just borrow my friends o2 sensor socket and get it out that way I don't have to try and crimp that connector on the end of the new one while its down in the car. Thanks again for the feedback and suggestions. Have an awesome weekend.

 

You don't have to crimp the wire on the new one while its in the car. Take the connector from the old one and splice it onto the new one before install it, then it will connect back up with the other end.

 

I was saying that I would have to splice it while it is in the car if I used the regular socket approach. If I splice it out of the car then the regular socket wouldn't work. Right?

 

Oh, sorry, thats correct. Unless you are able to use a wrench to install it.