Definition of the P0406 code
P0406 is a generic ODB2 error code that indicates a fault in the EGR exhaust gas recirculation circuit. This code is similar to P0400, P0401, P0402, P0403, P0404, P0405, P0407, P0408, P0409.
What does the P0406 code mean?
P0406 means that the exhaust gas recirculation (EGR) A sensor has a high circuit voltage. The ECU detects this high voltage and the Check Engine light comes on. The Check Engine light comes on in the instrument panel.
What causes the P0406 code?
- EGR valve failure
- Excessive carbon accumulation
- Open circuit or short circuit in the wiring harness
- Poor electrical connection
- EGR valve vacuum line leak
What are the symptoms of code P0406?
- In most cases, the driver may not notice any symptoms other than the check engine light coming on.
- Some vehicles may experience slight fluctuations in engine speed and rotation.
- In rare cases, pinging may occur with the heaviest load and the engine may stall.
How can a mechanic diagnose the P0406 code?
- Use the check tool to check the history, pending and current codes.
- Take note of the freeze frame data, such as vehicle temperature, running time, and load at the time of the malfunction.
- Deletes the code
- Performs a test drive, attempting to duplicate frozen frame data conditions.
- Perform a visual inspection for damaged or worn wires, damaged vacuum lines, and loose electrical connectors.
- Use a scan tool to view the position of the EGR during startup and operation and the manifold pressure.
- Check for carbon buildup in the EGR valve, which causes the valve to not open and close properly.
Common errors when diagnosing code P0406.
Diagnosing a P0406 code can be a simple matter or turn into a nightmare if the diagnosis is not performed step by step and all necessary steps are not taken. This can cause the real problem to be overlooked and unnecessary repairs to be made.
How serious is the code P0406?
The P0406 code has a wide range of symptoms that can vary from just the check engine light coming on to the vehicle not keeping running or driving poorly. Use caution when driving vehicles with driving problems.
The P0406 code should not prevent you from driving the vehicle to a safe place after the malfunction occurs.
What repairs can a P0406 code repair?
- EGR valve replacement
- Repair or replace the wiring harness if necessary.
- Repair poor electrical connections
- Replace vacuum line
- Cleaning excessive carbon buildup
Additional notes on code P0406
- In some cases, the EGR valve and system can be cleaned. There are specialized cleaners that are used to break down the carbon so that it can be cleaned.
- Follow the instructions on the cleaner, but some EGR valves can have the carbon removed and function properly and do not need to be replaced.
