What Does P041A Mean?
The PCM has detected a general circuit fault with the exhaust gas recirculation (EGR) temperature sensor B. This sensor monitors the temperature of exhaust gas in the EGR passage to verify proper EGR valve operation. A circuit fault means the sensor signal is missing, stuck, or outside the valid voltage range. The driver may notice the check engine light, and in some cases slightly increased NOx emissions or a mild ping under load.
Common Causes
35%
Failed EGR temperature sensor B (open or shorted thermistor element)
30%
Damaged or corroded wiring/connector at the EGR temperature sensor
15%
Excessive carbon buildup on the sensor probe causing inaccurate readings
12%
Open 5V reference or ground circuit shared with other sensors
8%
PCM internal failure on the sensor input circuit
Diagnostic Steps
1
Locate EGR temperature sensor B (typically mounted in the EGR passage or pipe downstream of the EGR valve). Inspect the connector for heat damage, corrosion, or loose pins.
2
With the sensor disconnected, measure the thermistor resistance. At room temperature (~70°F/21°C), expect 50K-100K ohms (NTC type). At operating temp (400°F+), resistance should drop to 1K-5K ohms. An open or zero reading indicates sensor failure.
3
Verify the 5V reference voltage at the sensor connector (key on, engine off). If missing, check the reference circuit back to the PCM — it may be shared with other sensors.
4
Check ground circuit continuity from the sensor connector to the PCM ground pin — should be below 0.5 ohms.
5
If the sensor and wiring check out, monitor the sensor voltage PID on the scan tool while warming the engine. The voltage should transition smoothly from ~4.5V cold to ~0.5V at operating temperature.
Estimated Repair Cost
$80 - $350
Parts + labor, varies by vehicle and location
The PCM has detected a general circuit fault with the exhaust gas recirculation (EGR) temperature sensor B. This sensor monitors the temperature of exhaust gas in the EGR passage to verify proper EGR valve operation. A circuit fault means the sensor signal is missing, stuck, or outside the valid vol...
The most common cause of P041A (Exhaust Gas Recirculation Temperature Sensor "B" Circuit) is: Failed EGR temperature sensor B (open or shorted thermistor element)
Typical repair costs for P041A range from $80 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Generally safe to drive short distances. Without accurate EGR temperature feedback, the PCM may not properly control EGR flow, which could lead to increased NOx emissions and potential engine knock/detonation under heavy load conditions. Avoid sustained heavy throttle until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P041A to identify the root cause.
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Quick Info
Category
Powertrain
System
Exhaust Gas Recirculation (EGR) System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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