Enter the error code and car brand

Vehicle engine and/or automatic transmission

Code: P0597 - The thermostat heater control circuit is open, meaning the engine’s thermostat (which controls temperature) isn’t getting the needed electrical signal.

Let me break down p0597 for you-this code stands for “Thermostat Heater Control Circuit/Open.” What’s happening here is your engine’s computer (whether it’s called a PCM or ECM) is trying to talk to the electronic thermostat, but it’s not getting any response back. These days, a lot of engines use electronic thermostats so the computer can dial in the exact temperature for peak efficiency and cleaner emissions. The thermostat is basically a valve that manages coolant flow, keeping your engine in that sweet spot-not too hot, not too cold. When the PCM sends a command and sees zero voltage in the control circuit for a stretch of time, it throws the code. Think of it like you’re calling someone and all you get is dead air. That’s what your car’s computer is experiencing.

Causes of obd code P0597

From experience, the most common reasons I see for a p0597 code are:

A faulty electronic thermostat (the internal heater or valve fails)
Wiring problems-like broken wires, corroded connectors, or loose plugs in the thermostat circuit
Issues with the PCM itself (rare, but possible if everything else checks out)

Most often, it’s the thermostat or the wiring at fault. I recommend starting your checks there before suspecting the computer.

Symptoms of P0597 trouble code

When this code pops up, here’s what you might notice:

The check engine light comes on-sometimes that’s the only clue
The engine temperature gauge might read unusually high or low, or bounce around
The radiator cooling fans may run longer than normal, even when the engine isn’t hot

In some cases, you might not notice anything right away, but ignoring it can lead to bigger problems down the road.

Diagnosis steps for P0597 code

Here’s how I usually approach diagnosing a dtc p0597:

First, I check the basics-make sure the coolant level is correct and there are no obvious leaks. Low coolant can sometimes cause odd readings.
Next, I visually inspect the wiring and connectors at the thermostat. Look for broken wires, corrosion, or loose plugs. It’s best to have someone wiggle the harness while you watch for changes.
With the ignition off, I disconnect the thermostat connector and check for bent pins or moisture inside.
Using a multimeter, I test for power and ground at the thermostat connector. If either is missing, I trace the wiring back toward the PCM.
If the wiring checks out, I use a scan tool to command the thermostat and watch for a response. If there’s no change, the thermostat itself is likely bad.
Only after all these steps would I suspect a problem with the PCM, and that’s pretty rare in my experience.

Don’t forget to double-check the repair manual for your specific vehicle-some models have unique wiring layouts or test procedures. This error can also happen on car brands like Chevrolet, Opel, and Vauxhall.

Common mistakes with obd2 code P0597

I’ve seen folks jump straight to replacing the thermostat without checking the wiring or connectors first. That’s a surefire way to waste money if the real issue is just a loose plug or corroded pin. Another common mistake is ignoring the code because the car seems to run fine-things can go south quickly if you leave this unchecked. Always make sure to rule out simple electrical faults before replacing expensive parts.

Seriousness of P0597 engine code

This isn’t something you want to put off. If the thermostat isn’t working right, your engine can run too cold or too hot. Either way, you risk poor fuel economy, higher emissions, and even engine damage if overheating occurs. In the worst case, you could end up with a warped cylinder head or blown head gasket. Honestly, it’s dangerous to ignore this-fix it before it leads to bigger headaches.

Repair procedures for P0597

Here’s what usually fixes a gm dtc p0597 00:

Replace the electronic thermostat if it’s faulty
Repair or replace any damaged wiring or connectors in the thermostat circuit
In rare cases, reprogram or replace the PCM if it’s confirmed to be the culprit

After repairs, always clear the code and test-drive the vehicle to make sure it doesn’t return. I personally recommend using OEM parts for the thermostat to avoid repeat failures.

Conclusion

To sum it up, P0597 means your engine’s electronic thermostat control circuit isn’t working as it should. It’s important to address this quickly-otherwise, you could face engine overheating or other serious problems. Start with the simple stuff: check wiring and connectors, then move on to the thermostat itself. Most of the time, replacing the thermostat or fixing a wiring issue will solve it. Don’t let this one slide-your engine’s health depends on it.

Video for "Error p0597" on YouTube