Error code

OBD2 P0405

OBD2P0405
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Exhaust Gas Recirculation Sensor 'A' Circuit Low.

Severity

moderateCan drive but may experience slight performance and fuel economy issues.

Summary

P0405 indicates that the EGR valve position sensor A is reporting a low input signal to the ECM, which could be due to wiring issues or a faulty sensor.

Symptoms

  • Malfunction Indicator Light (MIL) illuminated
  • Potential slight drop in performance and fuel economy

Common Causes

  • Faulty EGR position sensor A
  • Wiring issues or poor connections between the sensor and ECM
  • Technical Service Bulletins (TSBs) for specific models addressing P0405/P0406, requiring reprogramming of the ECM

Diagnosis

  1. Check for obvious damage to wire harness, such as chafing or burns
  2. Test the EGR position sensor with a digital multimeter (DMM) and vacuum pump if applicable
  3. Measure resistance on the three wires of the sensor and check for shorts

Fixes

  • Replace faulty EGR position sensor A

FAQ

What should I do if my MIL is illuminated due to P0405?

Check for wiring issues and test the EGR position sensor. If necessary, replace the faulty sensor.

Can reprogramming the ECM fix P0405?

Yes, some models have TSBs that address this issue through ECM reprogramming.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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