I just bought a '90 civic wagovan with 1.5. Right off the bat I noticed the temp gauge only works some of the time, and after driving for awhile the check engine light comes on. Well before going out and buying a temp sensor, I thought I would check the code, but no codes come up. So I thought maybe I needed to check it with the check engine light on (thinking maybe it loses the code after turning the car off) So I drove around till the light came on, and still nothing, no blinks, the light just stayed on. I could use some help if anyone knows what might be going on. Oh and I havn't noticed the fan coming on either. I'd appreciate any help I can get. Thanks!!!

Edit... The check engine light comes on when I turn on the key and goes off after two sec. like it's suppost to, and It only comes on after driving for quite awhile (like 20 min.) And when I check for codes with the key turned on, i get nothing. The light doesn't come on or flash.

 

if its obd0 you need to look at your ECU for the code. It has a red light on it that blinks when you have a code. the actual CEL wont change.

 

Oh really? Dang, I have to pull up the carpet then? Isn't it located under the passenger side carpet? Thanks for the response!!

 

Well I pulled the carpet, found the little window, and turned the key on. I got the red light blinking, but it blinks pauses for like 2-3 sec and blinks again. I was counting the blinks but stopped at 50 something. Does this mean code 1 or should I of kept counting? Or do I have to check after the CEL comes on?

 

code 1 im having the same problem

check the wiring from o2 all the way to the ecu

 

Hmm, ok. Isn't there two o2 sensors though? Which one should I check? I must have an o2 sensor problem and a temp sensor problem, but only getting code 1.
And would the temp sensor keep my fan from coming on?

 

Try just replacing your o2 sensor with a new one. And efs usually have only one on the top part of the header. I randomly get a code one like once a month but haven't changed mine yet. Too much snow lol

 

you still haven't fixed that o2 problem mija...!!!

 

If you want to do this correctly, don't just run out and change the O2 sensor.
Test your existing sensor and see if it's working or getting lazy/failing.
If it's working then you have a totally different problem.
Replacing the sensor may clear your code, but whatever caused the failure to begin with will continue and you will eventually end up with the CEL all over again.

 

Thanks everyone! I'm thinking that it's the temp control sensor. I guess that could be throwing the o2 sensor code and the reason my fans arn't working either, because the computer doesn't know that the car is heated up. I bought one, and it was cheap enough to where it doesn't really matter if that's the problem or not. At least I'll be learning something new haha. I do hope it works for me though, my dodge gets 15 mpg and It's killing me!!!!! I want 35 mpg minimum lol I never got less than 38 mpg with my last wagovan. Thanks again!

 

Well I guess I didn't learn anything new, that was as easy as my best friends mom. Except I didn't know coolant would pour out (make sure you have your new part ready to throw in lol.) Gonna take her for a drive and see if my problems solved.

 

The fan doesn't hook up to the computer in any way shape or form.
It runs on an independent circuit that consists of a relay behind the headlight and a temp switch near the oil filter.
This is an easy check.
1) check fuse.
2) Disconnect the fan and hook it directly to the battery (doesn't matter which way - it will spin or it won't) to make sure the fan works.
3) Find the 2 prong temp switch next to the oil filter and disconnect it. Jump the connector wires together and turn the ignition to 'on'. Fan should spin... if it does then your temp switch is dead (or the connector wasn't on right). This is very common - sometimes it gets disconnected when changing oil filters.
4) if jumping the temp switch didn't work then troubleshoot your relay and wire loom.

 

I checked the fuses, and they're all good. I just put in a new temp sensor, so that's good, unless the connection is dirty (and I plan to clean that tomorrow when it's not 10 degrees outside lol) My main concern is not the fan though. I will get to that soon. (unless the fan switch would cause my temp gauge to act up, and throw an o2 code) What I'm really concentrating on is the temp gauge only working half the time. I'm going to look into the temp sender? I think I may have more than one problem.

Ok, just to clarify: My problem is the temp gauge only working part of the time and after like 30 min of driving I get CEL with an o2 code. And my fans don't come on (there are two, which is not show in my chilton manual) I will try what you said about the fan switch, but there's no way all these problems could be related, could there?

I'm guessing temp sender may fix the temp gauge problem, and probably just replace my o2 sensor, and that will take care of the CEL. And then I will work on what you said for the fans. I'd appreciate any input you have to help me through this.

Oh, and I tried pulling on the plastic boot next to the oil filter on the back of the engine and I couldn't budge em (there are two different ones back there, and I was trying to check em out) They seem to be connected well. And which one is the fan switch? I thought that was on the thermostat housing or something. It's a d15b2. Oh, and visually my relays are ok. I already checked em.
What a day, I want my car to get well! Should I send it flowers? haha