EGR problem
The engine light on my 2009 Mazda6 2.2 D came on after pulling out from the drive, so I turned the car around, parked it on the drive again and read the codes with my portable scanner. The only code that turned up was ‘P0406 – EGR Sensor A Circuit High’ (both pending and current – same code). I cleared the code, restarted the engine and all seemed fine. I made it to work having a good run of about 15 miles on the A3 with my foot to the floor when I could. The light did not come back and the fuel economy was normal at about 50mpg.
The DPF had regenerated the day before this problem occurred, as I drove an extra few miles on the A3 to let the soot burn out completely. I know that the fuel economy can go up and down depending whether or not I am accelerating, but I always double-check the average mileage and that also goes down significantly when the DPF regenerates, usually by about 3mpg. I also recently cleaned the turbo and EGR valve, without dismantling the valve, using Wynn’s sprays. That was about 2000 miles ago.
Would dismantling and cleaning the EGR valve be the best way forward before the problem reoccurs? I would be grateful if you could describe the procedure to do this. The reason why I did not dismantle it in the first place was because it’s in close proximity to high-pressure fuel lines and I didn’t want to start the job without knowing the right procedure. Bartosz Kijanski The code ‘P0406’ refers to the EGR solenoid valve operation and the fault may be due to a sticky solenoid, an electrical fault in the solenoid or a fault within the loom. If the problem is a sticky solenoid, it can often be freed off by cleaning and its operation restored. However, if the solenoid has an electrical problem, then a new valve will be required. As you have used the EGR cleaner without success, it is likely that the problem is within the electrical solenoid as opposed to a sticky solenoid.
The EGR valve is secured from the front by two bolts and fitted to the elbow on the EGR cooler. Removal is quite straightforward, and if you need to remove the high-pressure diesel pipes, they can safely be undone after allowing the system to rest for 10 minutes after running. After this time, the pressure will have dropped.