Error code

OBD2 P0408

OBD2P0408
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Exhaust Gas Recirculation Sensor 'B' Circuit High.

Severity

moderateCan drive, but performance and fuel economy may be affected.

Summary

P0408 indicates that the EGR sensor B circuit is reading high input values, which can affect exhaust gas recirculation control in your vehicle.

Symptoms

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

Common Causes

  • Faulty EGR position sensor B
  • Wiring issues or shorts to positive in the EGR sensor circuit
  • ECM programming issue (specifically for Dodge/Chrysler/Jeep/RAM/MOPAR models)

Diagnosis

  1. Check for obvious damage to the EGR sensor wiring harness
  2. Test the EGR position sensor B with a multimeter
  3. Inspect circuit resistance between the ECM and EGR sensor

Fixes

  • Replace faulty EGR position sensor B

FAQ

What should I do if my MIL is on due to P0408?

Check the wiring and sensors related to the EGR system. If issues are found, repair or replace them as needed.

Can I drive with a P0408 code?

Yes, but performance may be slightly reduced and fuel economy affected until the issue is resolved.

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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