P23E6: EGR C Control Stuck Closed

With P23E6 the module concludes that EGR valve C does not open when commanded and stays at or near its closed stop. The consequence is the reverse of P23E5: the engine runs smoothly, but the exhaust share from this path is missing, combustion temperature and NOx go up, and a petrol engine may knock more readily. Typical reasons are a valve glued shut by soot, a seized shaft, a stripped drive gear or a motor that no longer delivers enough torque against the deposits. The counterparts for valves A and B are P042F and P045F; GM's 2018 diesel tables group P042F with P042E as position deviation faults. No manufacturer documents P23E6 publicly; CARB requires EGR systems to be monitored for insufficient flow and faulty control. Low flow from this path is P23E7.

Medium severity. Can I keep driving?You can normally drive in moderation, but get it repaired soon: if the valve is stuck open, the engine may idle very poorly.

Symptoms

No change in driving, but higher NOx
Possible knocking on petrol engines
Warning lamp

Most likely causes

Valve C glued shut by soot
Seized shaft or stripped drive gear
Actuator motor too weak to break the valve free

What to check, in order

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

Check the connector and any vacuum hoses
Use the scanner to command the movement and compare the actual position with the requested one.
Use live data to compare the commanded opening with the actual opening
Clean the valve and passages if they are clogged with carbon
Test the actuator with the scanner
Replace the valve if it still does not follow the command after cleaning

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P23E6 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
3: Ignition and misfires
E6: Specific fault in that system

Frequently asked questions

Can I keep driving with code P23E6?

You can normally drive in moderation, but get it repaired soon: if the valve is stuck open, the engine may idle very poorly.

What causes code P23E6?

The most common causes are: valve C glued shut by soot; seized shaft or stripped drive gear; actuator motor too weak to break the valve free.

Related codes

Sources

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.