P041A

Code

Generic P — Powertrain

EGR Temperature Sensor B Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 25 EN: 43 RU: 27

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Page language: EN

Causes

Open or short in EGR temperature sensor B wiring
Poor or corroded connector/terminal at sensor or PCM
Failed EGR temperature sensor B
Damage from heat, chafing, or contaminants (oil/coolant/exhaust)
Intermittent connector contact from vibration
PCM input circuit fault or software anomaly

Symptoms

Mil (check engine) lamp illuminated
Possible reduced engine performance or limp behavior if PCM limits functions
Failed or elevated emissions and possible failed emissions test
Erratic idle or rough running in some cases
Related EGR control faults or reduced EGR duty/operation

What to check

Read and record freeze-frame and freeze-data with a scan tool; note conditions when code set
Check for additional EGR or temperature-related DTCs and compare bank A vs B readings
Visually inspect EGR sensor B connector and wiring harness for damage, corrosion, or heat exposure
Back-probe sensor connector and verify reference voltage (usually 5V reference) and good ground
Monitor live EGR temperature sensor B voltage/temperature while warming engine and compare to sensor A or expected trend
Wiggle wiring harness and connectors while monitoring live data to find intermittent faults

Signal parameters

Typical sensor output: 0.1–4.9 V signal to PCM depending on temperature (varies by design) — consult OEM for exact values
Open-circuit symptom: signal may read near reference voltage or float (e.g., ~4.9 V) or 0 V depending on circuit design
Short-to-ground symptom: voltage close to 0 V
Short-to-battery symptom: voltage stays near battery voltage (~12 V) — usually triggers a different set of codes
NTC thermistor-type resistances: higher resistance when cold, lower when hot (typical cold: kΩ range; hot: hundreds of ohms) — check OEM chart

Diagnostic algorithm

Connect a capable scan tool. Read and record P041A plus any related codes and live data for EGR temperature sensors A and B.
Clear codes and attempt to reproduce. Note the operating conditions (temperature, load) when code returns.
Visually inspect sensor B, connector, and harness routing near exhaust/EGR for heat damage, soot, oil, or coolant intrusion.
With ignition on (engine off), back-probe connector: verify sensor reference voltage (usually 5V) and ground continuity to chassis and PCM.
Start engine and monitor sensor B voltage/temperature on scan tool while warming. Compare to sensor A and expected trend. Wiggle harness/connectors for intermittent behavior.
If voltages abnormal, disconnect sensor and measure sensor resistance at the sensor terminals with a multimeter at ambient and warmed conditions; compare to expected thermistor behavior (resistance falls as temp rises).
Check continuity between sensor connector and PCM pin; check for short to ground or battery on the signal and reference wires.
Repair any damaged wiring, terminals, or grounds found. Re-test after repair. If wiring and connectors are good and sensor readings are out of spec, replace the EGR temperature sensor B.
After repairs or sensor replacement, clear codes and perform a drive/functional test to confirm the code does not return.
If fault persists with good sensor and wiring, consider PCM input fault and consult manufacturer procedures for PCM testing/reprogramming.

Likely causes

Broken/frayed wire in harness to EGR temp sensor B (open or short to ground/12V)
Corroded or pushed-back pin/poor ground at sensor connector
Failed/ageing thermistor or temperature sensor element
Connector contamination (corrosion, soot, oil) or water ingress
High-resistance ground or lost reference voltage to sensor

Fault status

⚠️ Status

PCM has detected an out-of-range, open, or short condition on the EGR temperature sensor B circuit. Inspect wiring, connector, and sensor; repair or replace as required.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours