What Does P0405 Mean?
The EGR (Exhaust Gas Recirculation) position sensor A is reporting a voltage below the expected minimum threshold. Despite the description mentioning 'range/performance,' P0405 specifically indicates a low circuit condition on the EGR sensor. This typically means the sensor signal is shorted to ground or the sensor has failed low. The driver may notice the EGR system is disabled, with possible increased NOx emissions and light engine knock under load.
Common Causes
30%
Shorted signal wire — the EGR position sensor signal wire is shorted to ground
30%
Failed EGR position sensor outputting low voltage
20%
Corroded or contaminated connector causing low-impedance path to ground
12%
Open 5V reference circuit to the sensor
8%
ECM internal pull-down or input circuit fault
Diagnostic Steps
1
With key on engine off, check the EGR position sensor voltage PID — it should read approximately 0.4–0.9V with the valve closed. A reading near 0V confirms a low circuit condition.
2
Disconnect the EGR sensor connector and check for 5V reference and ground at the harness side. If reference is missing, trace the 5V reference circuit back to the ECM.
3
With the sensor disconnected, check if the signal wire is shorted to ground using a DVOM between the signal pin and chassis ground — should read infinite ohms (OL).
4
Inspect the connector for moisture, corrosion, or carbon tracking between pins that could create a low-impedance path.
5
If wiring checks good, reconnect and backprobe the signal — if the voltage remains pegged low, replace the EGR valve/sensor assembly.
Estimated Repair Cost
$80 - $350
Parts + labor, varies by vehicle and location
The EGR (Exhaust Gas Recirculation) position sensor A is reporting a voltage below the expected minimum threshold. Despite the description mentioning 'range/performance,' P0405 specifically indicates a low circuit condition on the EGR sensor. This typically means the sensor signal is shorted to grou...
The most common cause of P0405 (Exhaust Gas Recirculation Circuit Range/Performance) is: Shorted signal wire — the EGR position sensor signal wire is shorted to ground
Typical repair costs for P0405 range from $80 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. The ECM will disable EGR operation, which may increase NOx emissions and cause slight engine knock under heavy load. The vehicle will fail emissions testing. No immediate safety risk.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0405 to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control / EGR System
Difficulty
Type
Generic (SAE)
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