7thgensurvivor

Hi all.

Done a bunch of searching, and still having trouble deciding what is wrong with my 2002 Honda Civic EX 1.7L Auto.

Got a check engine light on my dash this evening, noticed the engine temp gauge was very high, about 1 or two ticks below red.

Got home and noticed that although the vehicle was running very hot, the cooling fan was not running. Turned on my A/C and both fans turned on. Checked the relays and fuses and they seemed ok. Guessing it is either the ECT sensor or the thermostat. I tried taking the plug off the top of the ECT sensor and shorting it with a wire and later a paperclip. Neither one made the fan turn on. Note the car had cooled down by now.

Anyway, trying to figure out what to do next. Not sure how to determine for certain what needs to be changed or fix it.

Any ideas?

Thanks,

-- Peter

Pistons

I'm in the exact same boat as you with my 03 Civic....I had a mechanic I know look it over and he determined it's my ECT sensor. I was surprised to see Honda charging like $55 for this OEM part, so I'm wondering if I can buy aftermarket for this part and if so, where from considering I'm in Canada, if anyone can answer this I'd appreciate it

mikey1

let it cool down, then check the level in the rad and overflow bottle,

where are the levels at?

ezone

If you are overheating, you had better make sure the radiator itself is completely full of antifreeze.
(Just because you have a problem and it's a 7th gen, you probably need a head gasket job, if not more. )


The radiator fan switch is in the thermostat housing.




Disconnect the wires from the switch, turn the ignition key to ON ( engine not running) and use a short wire or paper clip to bridge the terminals in the harness connector. Fans should come on if relays and wiring are good.
This checks everything EXCEPT the temperature switch.

HTH

7thgensurvivor

Thanks for the reply ezone. I understand from reading on here that you are probably one of the most knowledgeable on this topic, so was happy to see your reply.

A couple of questions about what you said. You mentioned the radiator fan switch is where the thermostat housing is. I saw this last night, but couldn't figure out how to disconnect that unit. I'm sure there is a simple trick to it, but I couldn't pull or pry it off and didn't want to break it. How do you get it off?

In my case, both fans come on if I turn on the A/C, don't know if this means my switch is okay?

I started to suspect the thermostat and the ECT temp sensor. Then I read some more and I think I realized the thermostat will fail open, which shouldn't result in overheating and the cooling fan not coming on. So, that left me with the ECT sensor or the fan switch. I think the relay is okay. Not sure what the symptoms of head gasket problems are???

I tried shorting the plug that connects to the ECT sensor to see if that would get the fan moving, but no luck. Figure I could try the same with the fan switch if I could figure out how to get if disconnected.

I think I can avoid disaster til I get this figures out by riding with the A/C on cause that seems to get the fans moving.

Sorry for typos, on my cell at the auto parts store.

Thanks in advance.

-- Peter

7thgensurvivor

Feeling dumb now. The plug was easy to get off. Shorted the fan switch plug with a paper clip and the fan came right on. Guessing that means it's a bad fan switch. Thinking everything else is probably good.

ezone

Push the lock tab, then slide the connector off.
It's there, but it may not be pointed in a direction you can see it easily.
There's always a lock tab, unless some yoyo broke it off before you.


No it does not. The PCM turn the fans on when the AC runs, this bypasses the temperature switch.

The fan relays are ok though, the PCM uses the same ones that the temp switch would use.


Not always. It can be stuck closed, it could be that it can't open wide enough.... there are several different ways a thermostat can fail.

That only causes ECT code to be stored in the PCM.

Speaking of that, what codes do you have from the PCM?

ezone

It can take a loooong time to run the fans if you just sit there and wait, and the engine can be overheating without the fans needing to run---due to the location of the switch in relation to liquid flow.


Switch turns on at about 200F. You could remove it and do the boiling water check with an ohm meter connected to test it.

7thgensurvivor

Thanks again for the replies Ezone. Bought a replacement fan switch. Looks easy enough to change out. Unfortunately (or fortunately, I can't decide) the car seems to have healed itself for the time being. Fans are coming on as expected. Hard to tell if you are fixing the right thing when the problem is intermittent.

Didn't pull the codes yet. Don't have a code reader yet. Could do the paper clip trick again in the OBD port. sigh...