$8B Temp Sensor issue 2.3l HO Quad-4

**BigBanks78** · 07-19-2023

Hello Its been a while.
I just installed a rebuilt Quad-4 HO and went back to $8B. I kept getting the ses light after start up so i watched the data stream and seen the temp sensor reading 250+ degrees F until the engine temp gets to 121 F then reads normal to at least 192F. I checked the engine with a laser thermometer and the sensor boss temp was the same as the data stream. I tested a new sensor today by plugging it in without installing in the engine. the outside temps here are 95-100F, the new sensor read 256F while in my hand so i plugged the old sensor back in with the engine running and at 182F and the data stream went back to 182F.

Do i have the wrong type of coolant temp sensor? Did I scramble the code some how, I have had to build history tables and dashboards in the adx, maybe user error? Is there any new developments with $8B?

I always appreciate the advice!!!

**NomakeWan** · 07-19-2023

Rather than checking the datastream I would check the sensor's resistance to make sure it's working as expected.

If the sensor is good, then next you need to check two things.

1. You saw the SES light is on, but you didn't say what actual code was being thrown. This is very important. Please check to see exactly what code is being set.
2. Especially if the SES code has nothing to do with the coolant temp sensor, I would suspect your ADX is using an incorrect translation for the coolant temp sensor.

I have zero experience with $8B so I cannot offer specific advice. But always, always start with the basics.

**BigBanks78** · 07-20-2023

Originally Posted by NomakeWan

Rather than checking the datastream I would check the sensor's resistance to make sure it's working as expected.

If the sensor is good, then next you need to check two things.

1. You saw the SES light is on, but you didn't say what actual code was being thrown. This is very important. Please check to see exactly what code is being set.
2. Especially if the SES code has nothing to do with the coolant temp sensor, I would suspect your ADX is using an incorrect translation for the coolant temp sensor.

I have zero experience with $8B so I cannot offer specific advice. But always, always start with the basics.

I looked for the resistance specs when i bought the new sensor but figured it was a bad sensor based on passed experience so i didn't dig. New and old sensor both switch at the same temp, I will check the resistance as temp climbs and get the specs. The SES stays off if I wait till the sensor reads 121F or above and then kill it and restart. Yea i guess I forgot code 26 I think, high coolant temp. I probably got a bad one out of the box. I only asked because I built a dashboard and must have picked the wrong coolant temp pid cuz it read 60F when above 100 and hadn't had time to try again. (not the same adx)

**NomakeWan** · 07-20-2023

If the SES is indicating a coolant temp fault, then you have an incorrect sensor, or a faulty sensor. Pretty cut and dry.

**BigBanks78** · 07-22-2023

Originally Posted by NomakeWan

If the SES is indicating a coolant temp fault, then you have an incorrect sensor, or a faulty sensor. Pretty cut and dry.

I only have a code when the engine is less than 120F and the datastream says its 250F setting code 14. The code doesn't set after its warm. $8B as far as i know uses the same temp sensor as $0E (or is it $OE). The same part number "standard ignition, TX3" comes up. The sensors, all 4, 2 brands, have 3000 ohms at 70F and about 200 ohms at 220F with no jump in ohms at 120F. This sensor worked fine with code59 but not when i use $8B also works fine in my $0E 7.4l C3500 and this sensor is the only one that comes up when searching the most common ecms talked about here. It very well could be the wrong sensor, I just haven't found another option.

**NomakeWan** · 07-22-2023

Originally Posted by BigBanks78

I only have a code when the engine is less than 120F and the datastream says its 250F setting code 14. The code doesn't set after its warm. $8B as far as i know uses the same temp sensor as $0E (or is it $OE). The same part number "standard ignition, TX3" comes up. The sensors, all 4, 2 brands, have 3000 ohms at 70F and about 200 ohms at 220F with no jump in ohms at 120F. This sensor worked fine with code59 but not when i use $8B also works fine in my $0E 7.4l C3500 and this sensor is the only one that comes up when searching the most common ecms talked about here. It very well could be the wrong sensor, I just haven't found another option.

The important thing to recognize here is that the datastream is not setting Code 14. If Code 14/15 are being set, that means the ECM is actually seeing those inputs from the coolant temp sensor. That rules out a bad conversion in the ADX or your interface software.

Setting a code means the ECM actually detected a fault. So what you're seeing in the datastream is indeed what the ECM is seeing.

Bad sensor, wrong sensor, or sure, bad wiring between the sensor and the ECM. Check your grounds, too.

**BigBanks78** · 07-22-2023

Hey,
I checked the ohms on 4 different sensors from 70F to about 220F, range was 3000 @ 70, 200 @ 220. The ohms climbed smooth with no spikes. this sensor is the same used on the 7427 and 90's vette. stock form was a 1990 grand am. Yea and sorry I was getting code 14 coolant high not 26 QDM, then today after good and heat soaked I got a code 15 coolant low........ wheres the "slapping my forhead" emoji... Im going over the wiring for the 50th time but after that I guess ill deal with it :)