DTC 0126

[Big T]

The '99 threw DTC P0126:

P0126 Insufficient ECT for Stable Operation

What's insufficient ECT? What is ECT?

I was able to clear the code and it did not return. I am at 6,750' elevation and temps are 32 F, if that helps.

 

[THEFERMANATOR]

ECT is engine coolant temp. If you had a scanner to see what it is seeing you could narrow it down real quick. Most likely causes are either a T-stat not closing to allow the engine to come up to temp in time, a bad CTS, or a bad connection to the CTS. The code is set either because the temp is to low to the ECM(connection unplugged or the CTS is failed to an open circuit), or it is taking to long to warm up(I believe the ECM sets this code if it takes longer than 20 minutes to reach 174 degrees).

 

[Big T]

That explains it. I started and left it idling for awhile. It only warmed up to 174 F when I drove it.

 

[hookedup50]

My 97 threw that code when the Tstats stuck open.

 

[THEFERMANATOR]

180 t-stats in the winter time can also throw it.

 

[Big T]

I've been throwing this code about once a month now. Recently I noticed that the temp gauge has been running two ticks below 185 F at highway speed on level ground. Normally it would run a tick over 185. Coming down from Big Bear the temp was close to 160.

Is it likely that my T-stats are stuck open?

 

[Will L.]

Yeah, double check the connection on your temperature switch while you are at it, but get ac delco t-stat only.
You could verify the coolant temperature to make sure, but 1 sensor sends signal to your temp gauge, and another for the code to get set iirc. So both sensors bad at same time would be odd.

 

[JMJNet]

I've been throwing this code about once a month now. Recently I noticed that the temp gauge has been running two ticks below 185 F at highway speed on level ground. Normally it would run a tick over 185. Coming down from Big Bear the temp was close to 160.

Is it likely that my T-stats are stuck open?

Yes.

 

[Big T]

So after some erractic temps, sometimes working and sometimes not, I finally got around to changing the T-stats. I opened the two AC Delco 195 T-stats ordered from RockAuto and thought the part #s were the same, the T-Stats were different. One matched those that I pulled from the truck, the other had a tall backside portion that pointed towards the radiator. Both fit in the dual T-Stat housing. One of the T-Stats that I pulled out was clearly broken or stuck and the backside portion fell off. I inserted the matching new one in its place and went with one old but working one and one new one. I test drove it and it goes to a tick above 185 and stays there, or quickly drops if it briefly goes above that spot. So I'd have to conclude that it's fixed and that one T-stat was definitely screwed up.