Thread: Pending p0128 code today

It popped up on the scan guage today. It was about 15c and when I shut the car off I noticed the fan was running which I couldn't hear over the exhaust. I think the guage said the coolant temp was 80c. It's been that way all summer, even if it's 25c out, it never got to 100c. I have heat extractors in the hood to aid in airflow through the radiator. I double checked the coolant a couple weeks ago and it's full. This is in a fiero

Off memory.. it's 128 typically a thermostat stuck open?

It points to that or the cts. I don't think its the cts as at the beginning of the day the ait and cts are the same and the cts goes up as the engine warms up. I like the fact that i'm running cool like that.

Keep in mind... you are only seeing one of the two ECT sensors that are built into the single package sensor that we replace.

If the pcm tossses a code and the dash is correct. It's wiring or sensor.

Originally Posted by BillBoost37

Keep in mind... you are only seeing one of the two ECT sensors that are built into the single package sensor that we replace.

If the pcm tossses a code and the dash is correct. It's wiring or sensor.

could you elaborate more on the sensor your talking about? Does that mean there's two different sensors on the motor or just the one that has two readings? The thing with the fiero dash gauges is they ain't reliable, mine barely goes to 1/4 on the guage but that might be correct just hard to tell with the lack of numbers.

id check the t stat, if its open you found the problem. stuck open will run to cold. these engines like to run at 210.

the temp sensor under the t stat, it sends info to the pcm. and the cluster gauge, some times 1/2 of the sensor quits working, or the wires are cooked from the heat of the cross over pipe.

You had mentioned that the coolant temp aka engine coolant temp (I noticed I used a different acro than you). The S2 has two sensors built into the one unit. There's three wires. One incoming and two outgoing. Of the two outgoing one feeds the pcm and the other feeds the dash gauge. Your mention of the CTS/AIT etc led me to believe the dash was reading the correct temp. Which would mean the code is being thrown based on a bad sensor to the pcm.

I'd prefer to check the reading of the pcm coolant temp with a scan tool. If the engine warms up and the temp doesn't read the change, then it's the sensor, if the temp of the engine actually does not warm up fast enough, it's a t stat

Originally Posted by Scottydoggs

id check the t stat, if its open you found the problem. stuck open will run to cold. these engines like to run at 210.

the temp sensor under the t stat, it sends info to the pcm. and the cluster gauge, some times 1/2 of the sensor quits working, or the wires are cooked from the heat of the cross over pipe.

Ahh gotcha, will look at the sensor. Just to learn me, I know the thermostat stays closed until it reaches it's temperature. Once it's open, won't it cool back down to where it would be if it was stuck open? Like in my situation, I'm usually around 80c (say it's stuck open) and I replace it with a new one. The temp gets to 180 and opens, won't my temps eventually go back to what I'm seeing now? I'm hoping I have a kick ass cooling system and never have to worry bout it overheating. And I do have heat out of the heater.

when a t stat fails they can fail open, or closed. (depending on the brand) when stuck open it can run to cold.

180 t stat is to cold too. put a 195 in like it wants. modded or not the engine runs its best around 200 to 210. getting cooling temps down is old school stuff dont apply to these newer engines.

What out Scott...

He's BC. One sentence he's talking C's and then a moment later he says 180...which has to be F's Then northern neighbors of ours are always trying to trip us up

Originally Posted by BillBoost37

What out Scott...

He's BC. One sentence he's talking C's and then a moment later he says 180...which has to be F's Then northern neighbors of ours are always trying to trip us up

Lol, wasn't aware the 180 was f. So I need to figure out what that is here. But since I'm changing thermostats, I will be modding the motor in the future should i go for the lower one? Keep in mind this is only a summer driven vehicle.

this is a US based site. so i talk degree's damn it lol i dont do canuch temps hahahahaha.

195 fahrenheit t stat always, year round.

i went the extra mile for ya. 195 is the same as 90.5556 c

212F = 100C
32F = 0C

If you are seeing close to 100C then you are at the normal T stat which is 195F

i see Bill went a mile further lol

Originally Posted by Scottydoggs

i see Bill went a mile further lol

Which..is way longer than a Kilonomonolomter

lmao.

100KPH is 62.5mph.. wanna talk about feeling lethargic while driving. Can't speed, cause you are in another country...

Originally Posted by BillBoost37

212F = 100C
32F = 0C

If you are seeing close to 100C then you are at the normal T stat which is 195F

like I said in the title it's pending. So it seems like the temps are normal then. So I wonder what might be issue. I might just wait to see if it actually pops up.