EGR error
Q: I recently bought a 2007 Kia Sportage 2.0D XS four-wheel drive with engine number D4EA6H23486 and a diesel particulate filter. The emission light is on and there is error code ‘P0401 – EGR flow insufficient’. I was wondering what is wrong and what to check first? The engine runs fine and it has just had a new air filter and fuel filter. Mervyn Stead
A: The code is indicating that there is a blockage in the system which is preventing the correct air flow through the EGR valve. This may be due to a blocked pipe or a fault in the EGR solenoid that is preventing it from opening fully. However, the code can also be triggered by a leak from the exhaust system. For this reason, it is best to check for any leaks from the exhaust first. A weak battery can also cause problems, as can a faulty temperature sensor in the EGR circuit.
From the information I have on your Kia, the EGR valve is operated by a vacuum switch controlled by the ECU. The vacuum control valve is located at the back of the engine bay, on the bulkhead to the offside. The vacuum hoses should be checked for leaks or cracks, as should the security of the electrical connections.
If no fault can be found here, then the connecting pipes should be inspected for excessive carbon build-up. It may be possible to clean these out using an EGR cleaning spray, but if the build-up is too extensive, then removing the pipes and EGR valve to clear the carbon will be required.
It is also possible that the vacuum operation system of the EGR valve has failed. This can be tested by applying a vacuum to the valve and checking for movement. If no movement is found, the valve will need to be replaced.