P23E5

Code

Generic P — Powertrain

EGR C Control Stuck Open

Brand: Generic

Type: P — Powertrain

Views: UK: 27 EN: 53 RU: 21

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Page language: EN

Causes

Carbon build-up or deposits mechanically holding EGR valve open
Faulty EGR valve (stuck or seized)
Faulty EGR control solenoid (stuck open) or vacuum source stuck on
Wiring short to power or ground in EGR control circuit, or poor connector/terminal
Faulty EGR position sensor or incorrect sensor input to PCM
PCM software or internal fault (less common)

Symptoms

Rough or erratic idle
Stalling at idle or low speed
Reduced engine power and poor throttle response
Increased NOx and failed emissions test
Black smoke under heavy load (diesel/high-EGR conditions)
Check Engine Light / MIL illuminated with P23E5

What to check

Read freeze-frame data and confirm P23E5 is current vs historic
Use a scan tool to view live EGR parameters: commanded position (% or duty), actual EGR position/voltage, and EGR flow if available
Visually inspect EGR valve, solenoid, vacuum lines (if vacuum operated) and electrical connectors for damage, corrosion or disconnection
Listen for vacuum leaks or hissing around EGR lines and intake manifold
Check for related codes (EGR position, pressure sensor, MAF, MAP, ECM communication)

Signal parameters

EGR position sensor output (typical): ~0.5–1.5 V = closed, ~3.5–4.5 V = open (varies by manufacturer)
EGR commanded position: 0% (closed) to 100% (fully open). Code indicates commanded closed with actual open
EGR solenoid coil resistance: typically 10–50 ohms (check service data)
Solenoid supply voltage: battery voltage when commanded on; ground present when commanded by PCM (or PWM control)
Vacuum-operated EGR: vacuum present at valve when commanded open, vacuum ~5–20 inHg depending on system

Diagnostic algorithm

Confirm the code and capture freeze-frame/live data: note engine load, RPM, coolant temp, commanded EGR and reported EGR position when code set.
With engine at operating temperature, use a scan tool to command EGR C closed and monitor actual EGR position/voltage and engine response. If commanded closed but actual remains open, proceed.
Perform visual inspection: check EGR valve/solenoid connectors, wiring harness for chafing, pin corrosion, broken wires and secure grounds. Repair any obvious issues.
For vacuum EGR systems: isolate vacuum lines; check for continuous vacuum at valve when EGR should be closed. Test vacuum solenoid operation by applying vacuum and releasing per service procedure.
For electronic EGR actuators/solenoids: backprobe connector and verify control voltage/PWM from PCM and ground continuity. Measure coil resistance and compare to spec. Apply bench or controlled supply per service manual to actuate valve and confirm movement.
Inspect/clean the EGR valve and passages: remove valve and check for carbon deposits preventing closure. Clean or replace if mechanically stuck or contact surfaces are damaged.
Check EGR position sensor: with valve mechanically closed, verify position sensor voltage/reading is within closed range. Replace sensor if out of range or intermittent.
If wiring and components test good, swap or substitute a known-good EGR solenoid/actuator if available, or inspect PCM outputs for shorts. Repair wiring or replace component as required.
Clear codes, perform a drive cycle and recheck. Confirm system returns to normal and readiness monitors complete.
If intermittent or unresolved after component replacement, consult manufacturer service information for module reprogramming or advanced diagnostics.