Constant code
QI am trying to solve a problem with my neighbour’s 2015 MINI Cooper Diesel 1.5. The car is an F56 series MINI. The car periodically illuminates the engine management light. The code generated is always P0471. If I clear the code using a fault code reader, it reappears a day or so later.
Upon a test drive, the car is powerful at all speeds and on the motorway, and it idles smoothly. The car is never in limp-home mode.
The MINI is regularly serviced with a full maintenance history going back to new. My question is how can I stop this fault code from being generated? I have changed the air filter as an additional check.
One thought I had was that the pressure sensor pipe for the exhaust pressure sensor may need cleaning? However, I do not know where the sensor is located, or where the pipe is.
Any advice you can offer and photos of components to check would be greatly appreciated.
Steven Jones
The code P0471 is indicating that the exhaust gas pressure sensor has a range or performance problem. This may be the sensor itself or it may be as you have suggested the pipes from the DPF to the sensor which are blocked preventing the sensor from reading correctly.
The sensor is located at the rear of the engine bay to the offside of the vehicle. This is a small sensor, and the connecting pipes will be seen coming from the sensor and going down to the exhaust.
This code does suggest a sensor failure more than a blockage as the code relating to DPF soot accumulation of blockage normally begin P24**
I would as you suggest first try cleaning the pipes to the sensor. If this makes no difference, then you should check that the sensor has a 5V feed to the plug by using a voltmeter between terminals 1 and 3 with the plug connected. If this is the case, then a further check that can be made is to test the output voltage at terminal 2 of the plug with the engine running. This should be around 1 Volt. This reading will increase if the DPF appears to become blocked.
The colour code for the terminals is terminal 1 = blue/grey, terminal 2 = black, terminal 3 = brown/orange.