P06AC: Control Module Internal Temperature Sensor B Range/Performance

Control modules can carry a second internal temperature sensor (B). In GM's 6T70/6T75 and related automatics, sensor A measures the circuit board (substrate) temperature, sensor B the 'power-up temperature' used as a reference and substitute; both sit inside the transmission module in the valve body, so repairs mean module or valve body. P06AC is the plausibility check of sensor B: GM compares the power-up temperature with the substrate temperature (sensor A) and the transmission fluid temperature and sets the code after two trips if they disagree beyond tabulated limits. Check the fluid temperature sensor (P0711) as comparison partner first.

Symptoms

• Warning or check engine light
• Changed shift quality (substitute value)
• Implausible module temperature in the scan tool

Most likely causes

• Transmission module or valve body (internal sensor) faulty
• Transmission fluid temperature sensor reads wrong
• Module supply or software

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the battery and grounds
2. Compare the reading with other engine data while varying the engine speed.
3. Clear the code and see if it returns
4. If it is a reference voltage code, disconnect sensors one at a time and see if the voltage recovers
5. Check whether a software update is available
6. Do not replace the control module without a full diagnosis

Good to know

• Repair difficulty: hard
• It can trigger limp mode.
• It affects emissions.

What each character of P06AC means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• 6: Control modules and outputs
• AC: Specific fault in that system

Frequently asked questions

Can I keep driving with code P06AC?

It depends on the symptoms. If the car is running normally you can go to a repair shop; if it goes into limp mode, drive as little as possible.

What causes code P06AC?

The most common causes are: transmission module or valve body (internal sensor) faulty; transmission fluid temperature sensor reads wrong; module supply or software.

Related codes

• P06ADControl Module Internal Temperature Sensor B Circuit Low
• P06AEControl Module Internal Temperature Sensor B Circuit High
• P06ABControl Module Internal Temperature Sensor B Circuit
• P0667Control Module Internal Temperature Sensor A Range/Performance
• P0711Transmission Fluid Temperature Sensor A Circuit Range/Performance

Sources

• law.cornell.edu: 13 CCR 1968.2
• gsi.ext.gm.com: 19OBDG03C Diagnostics
• saabwisonline.com: dtc p06ac p06ae

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.