P0408 Fault Code
P0408 OBD-II Trouble Code Short Description
Exhaust Gas Recirculation Sensor B Circuit High
What does trouble code P0408 mean?
The P0408 fault code indicates an issue with the Exhaust Gas Recirculation (EGR) Sensor B circuit being high. This code is related to the EGR system, which is responsible for reducing nitrogen oxide emissions by recirculating a portion of the exhaust back into the engine's intake system. When the sensor detects an abnormally high voltage or signal, it triggers this fault code.
Symptoms
What are the symptoms of the P0408 code?
- Check Engine Light (CEL) illuminated
- Decreased engine performance or reduced fuel efficiency
- Rough idle or stalling
- Increased emissions during vehicle inspection
- Possible overheating due to improper EGR operation
Causes
What causes the P0408 code?
- Faulty EGR Sensor B
- Wiring issues, such as shorts or corrosion in the circuit
- Poor connection or loose plugs in the EGR sensor circuit
- Malfunctioning Engine Control Module (ECM)
- EGR valve stuck closed or open
Possible Solutions
How to fix P0408?
- Inspect and repair or replace the EGR Sensor B as needed
- Check all electrical connections and wiring for damage or corrosion
- Test the EGR valve function and replace if necessary
- Clear the fault codes after repairs and ensure there are no lingering issues
- Conduct a thorough diagnostic to ensure related systems are functioning properly