Check engine light - Code 22 (1 Viewer)

[Spook50]

My light's been coming on and off sporadically over the last week, and when I pulled the code a few days ago it gave me a code 22 (temp sensor/circuit or ECU). My temp gauge has been working just fine (assuming that's even the sensor it refers to), so I'm wondering if the code is referring to one of the other temp sensors mounted in the thermostat housing or if there is a problem with my ECU. When the light comes on, I can feel a slight reduction in power as if I had let up off the gas, and if I goose the gas pedal, there's about a quarter second delayed reaction before the engine responds. No lugging, hesitation, racing, or anything else abnormal, and when the light is off, it's all running perfect.

Is it possible that one of the temp sensors is going out and making the ECU think that the engine's still cold when it's warm? The light is only coming on when the engine's warm. If that's the case, the question is: which damn sensor is it???

 

[slcfj62]

I haven't had a code 22 yet, but it sounds like a good candidate for the EFI knowledge pool thread I just started here:

https://forum.ih8mud.com/60-series-wagons/325371-3fe-efi-primer-knowledge-pool.html

I posted up three EFI diagrams that show there are three temp sensors monitored by the ECU. Coolant temp, EGR gas temp and intake air temp. There is probably a procedure in the FSM for checking each of those sensors. Based on your problem description, I'd guess either the EGR gas temp or the air intake temp. I don't think coolant temp would have such a drastic impact on performance.

So when you get it figured out, do a thread, and post the link in my EFI knowledge pool thread.

 

[Spook50]

I haven't had a code 22 yet, but it sounds like a good candidate for the EFI knowledge pool thread I just started here:

https://forum.ih8mud.com/60-series-wagons/325371-3fe-efi-primer-knowledge-pool.html

I posted up three EFI diagrams that show there are three temp sensors monitored by the ECU. Coolant temp, EGR gas temp and intake air temp. There is probably a procedure in the FSM for checking each of those sensors. Based on your problem description, I'd guess either the EGR gas temp or the air intake temp. I don't think coolant temp would have such a drastic impact on performance.

So when you get it figured out, do a thread, and post the link in my EFI knowledge pool thread.

EGR gas temp? Well that one can be eliminated easily enough, since my EGR system is completely removed from the truck. That leads to intake air temp. I'll look and see if there's anything I can find on it and hopefully I can figure something out.

 

[Spook50]

From the looks of the illustrations in the FSM, there are two collant temp sensors (that utilize connectors with two terminals) in the tstat housing. One for the gauge and the other for the ECU. Years ago I had the ECU one get so corroded that the whole connector fell clean off the sensor and needed to be replaced. Hopefully that's the case here and I can just swap the sensor and be good to go. I'm going to take a look at it today and see what's up.

 

[Spook50]

Update

Well sure enough, it was the sensor on the bottom half of the tstat housing. the one that connects directly to the ECU. I pulled the connector, checked for corrosion (it was good) and reconnected it, and haven't gotten the light for about two weeks now. I guess the connection just got jostled or something. Good to know that everything's still good there.