P23E2: EGR C Control Circuit Performance

P23E2 is raised when the drive circuit of EGR valve C is electrically intact but the valve does not respond to it as expected: commanded and measured position, or drive current and movement, drift apart. In GM's 2018 diesel calibration the A-side check P0404 compares setpoint and measured position of the high-pressure EGR valve and fails above a 10 % tracking error in 152 of 190 samples, with coolant at least 60 °C and outside air above −7 °C; it is a Type B code. Soot and lacquer, which over time stiffen EGR valves, are the usual reason, a worn gear train or a weak motor the next. No manufacturer documents P23E2 publicly; CARB asks that EGR control be checked for proper function. Circuit faults on valve C: P23E1, P23E3, P23E4.

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

Warning lamp after warm-up drives
Occasional hesitation when EGR is cut

Most likely causes

Soot and lacquer making valve C sluggish
Worn gears or linkage in the valve C actuator
Actuator motor of valve C losing torque

What to check, in order

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

Check the connector and any vacuum hoses
Compare the reading with other engine data while varying the engine speed.
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 P23E2 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
3: Ignition and misfires
E2: Specific fault in that system

Frequently asked questions

Can I keep driving with code P23E2?

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 P23E2?

The most common causes are: soot and lacquer making valve C sluggish; worn gears or linkage in the valve C actuator; actuator motor of valve C losing torque.

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.