OBD-II Generic Error Code P0408: How to Fix It

Q: Can I drive with error code P0408?

Yes, but it may cause reduced fuel economy, rough idling, and increased emissions. It is best to address the issue promptly to prevent further damage.

Q: Will a bad EGR sensor cause rough idle?

Yes, a faulty EGR sensor can cause incorrect EGR flow, leading to rough idle, stalling, or hesitation during acceleration.

Q: How much does it cost to fix code P0408?

If you DIY, the cost is typically $20-$80 for a new sensor plus cleaner. Professional repair can range from $100-$300 depending on labor and parts.

Q: What is EGR sensor B?

EGR sensor B is a temperature sensor that monitors the temperature of exhaust gas recirculated back into the intake. It helps the ECM control the EGR valve.

Q: Can carbon buildup cause P0408?

Absolutely. Carbon deposits can block the sensor tip or EGR passages, causing incorrect readings. Cleaning often resolves the code.

Abstract

Error code P0408 indicates that the Engine Control Module (ECM) has detected a voltage signal from the Exhaust Gas Recirculation (EGR) sensor 'B' that is higher than the expected range. This often points to a faulty EGR temperature sensor, carbon buildup in the EGR system, or wiring issues.