P04D1

Code

Generic P — Powertrain

EGR Temperature Sensor C Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 23 EN: 56 RU: 29

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open circuit (broken wire) in the EGR temperature sensor C signal/ground wiring
Short to battery voltage in the sensor signal circuit
Corroded/damaged sensor connector or poor pin contact
Failed EGR temperature sensor (thermistor open or out of range)
Poor or missing ground at sensor or ECM
ECM internal fault (less common)

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Possible reduced engine performance or limp mode if ECM disables EGR
Failed emissions test (EGR system disabled or not monitored correctly)
Stored freeze-frame data showing EGR temperature abnormal or unavailable
Occasional rough idle or drivability complaints if EGR is disabled

What to check

Retrieve freeze-frame and freeze data with a scan tool; view live EGR temperature sensor values and compare to ambient/intake/coolant temps
Visually inspect EGR temp sensor connector and wiring for corrosion, damage, melting or disconnection
Back-probe the sensor connector to measure signal voltage with ignition ON/engine running
Measure sensor resistance (with sensor unplugged) across signal and ground pins and compare to expected thermistor values
Check continuity and for shorts between the sensor signal wire and battery positive, and between signal and ground
Wiggle test wiring while monitoring live data or voltage to reproduce intermittent faults

Signal parameters

Reference voltage (from ECM): typically a stable ~5.0 V reference (verify OEM spec)
Sensor signal voltage: varies with temperature; typical range ~0.1–4.9 V across operating range (high reading or near battery voltage suggests open/short to Vb)
Sensor resistance: thermistor-based sensors will change with temperature (example typical ~10 kΩ at 25°C — consult OEM for exact curve)
A high-circuit condition often reads very high voltage (near battery voltage) or infinite resistance (open)

Diagnostic algorithm

Connect a diagnostic scan tool, read DTCs and freeze frame. Note conditions when code set (engine temp, load, time since start).
Visually inspect the EGR temp sensor, connector and nearby harness for heat damage, corrosion, chafing or disconnection.
With ignition ON (engine OFF), back-probe the connector and measure signal voltage. Compare to expected reference and signal ranges. A signal near battery voltage indicates a high/open condition.
With sensor unplugged, measure resistance of the sensor between signal and ground. Compare to expected thermistor values at ambient temperature. Infinite or out-of-range resistance indicates a failed sensor.
Check continuity from the ECM connector to the sensor connector for the signal and ground pins. Verify there is no short to battery positive on the signal wire.
If wiring and connector are good but the sensor reads open/high, replace the EGR temperature sensor and clear codes.
If fault persists after sensor replacement, check ECM power/ground and perform a voltage drop test on sensor ground. If wiring and grounds are good, consider ECM fault and pursue module testing or replacement per OEM procedures.
After repairs, perform a road test and re-scan to confirm code does not return and that live EGR temperature readings respond to changes.

Likely causes

Disconnected or corroded sensor connector
Broken / chafed wiring harness to EGR temp sensor (open)
Short to 12V in the sensor signal wire
Failed EGR temperature sensor element
Bad sensor ground or ECM ground circuit

Fault status

⚠️ Status

EGR Temperature Sensor C Circuit High — ECM detected abnormally high voltage or open circuit on the EGR temp sensor C circuit. May disable EGR monitoring and illuminate MIL.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

Repair manuals