1987 Honda Accord LX-i, PGM-FI light (Code 6)

Hello. I tried posting this last night but it didn't work for some reason. Trying again...

I recently bought a 1987 Honda Accord LX-i with 150,000 miles. The PO mentioned that the PGM-FI light has recently come on, and yes, the light is on at all times when the engine is running. I took a look at the ECU under the driver's seat to find the LED blinks six times, then repeats. According to online sources, this code is "Coolant Temperature" or ECT Sensor/Wiring problem (or a problem with the ECU itself).

The car does have a hard time with cold starts, and it will run badly for the first couple of minutes before warming up. Once it warms up, it runs much better, although still hesitates when accelerating from a stop. I already put 100 miles on the car since buying it a few days ago, and the fuel economy is worse than it should be (I used to own a 1984 Accord that got better mileage). Temp gauge goes up to 1/3, but then stays there not budging at all until shutting the car off. Oil is a bit dirty, but full and not contaminated. Coolant looks good, no leaks that I can find. I have not tuned the car up yet, I'm going to order the parts soon. But right now I want to take care of this PGM-FI light first.

So I'm about to order another ECT sensor from Rockauto, but it offers two different-looking ones for all models (including my fuel-injected LX-i). And on the thermostat housing, there are three sensors....I have no idea which one is the one I need to replace?

https://i.imgur.com/17h6Q3s.jpg

I did find one thread here that helps some, but it's eight years old and the image in that thread that would help me is long-gone now. The way I understand it is: One sensor is for the cooling fan, another is for the temp gauge in the dash, and the other is for the PGM-FI system itself? Which do I replace? And is my gauge working correctly since it only goes to 1/3 of the way (usually goes to 1/2 or slightly higher in my other cars, including my former '84 Accord).

The green plug is the one that throws code 6 the yellow one is for the fan switch and that little one is for the temperature gauge cluster. Most of the time the problem is the wire breaks right at the connector

Your gauge is working correctly. The TW sensor has most likely failed, but there's a possibility that a broken wire has triggered the code instead. It's worth going through the troubleshooting section on p. 12-26 of the manual to verify your problem before spending money.

I replaced the sensor this morning, fired it up and it ran perfectly. No more PGM-FI light. Thanks guys :)

Quote:

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Originally Posted by Dr_Snooz

Your gauge is working correctly. The TW sensor has most likely failed, but there's a possibility that a broken wire has triggered the code instead. It's worth going through the troubleshooting section on p. 12-26 of the manual to verify your problem before spending money.

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p. 12-23. Page 227/835 Got lost for a second searching. lol
Pointing it out for future reference when someone stumbles across here in a search.

Thx!