Typical C-MAX 2.0 TDCI faults

1

As its name implies, the Diesel Particulate Filter (DPF) system exists to remove particulate debris or soot from the exhaust. The system can be troublesome on this C-MAX.

4

The DPF pressure sensor is located within the air filter trunking. The sensor reports its pressure findings to the ECU, thus helping to correctly trigger the regeneration process when required (see Fault 2).

2

Here is one of the DPF temperature sensors, which monitors the degree of heat in the exhaust to enable automatic regeneration of the system when the temperature is high enough.

5

The mass airflow sensor (MAF) is also found in the air filter trunking. This sensor monitors the mass airflow rate of the air coming into the engine, in order that an appropriate mass of fuel may also be introduced, as triggered by the ECU.

3

The pressure within the DPF system is crucially important, since a build-up of ash will eventually clog it. As it becomes more obstructed over time, the internal pressure increases.

6

The vehicle’s battery is tucked away beneath a plastic cover and is shrouded beneath the engine compartment’s rear bulkhead, towards the left-hand side. It can be difficult to access (see Fault 3).

7

Make sure that the plastic cover for the underbonnet fusebox is fully fitted to ensure that moisture is kept out. This fusebox is located on the left-hand side of the engine bay.

8

The function of the Manifold Absolute Pressure (MAP) sensor is to assess the air pressure/density within the inlet manifold, delivering this information to the ECU so that correct fuel quantities are supplied. The sensor is bolted to the inlet trunking.

9

The fuel filter is critical to ensuring that only clean diesel is delivered to the fuel injectors. Don’t take chances and only use original equipment quality filters. The filter assembly is tucked away on the right-hand side of the engine bay.

10

Each fuel injector carries an individual barcode, containing data specific to that injector. When a new injector is introduced, it will come complete with a new code, which will have to be introduced to the ECU using diagnostic equipment.

11

The Bosch cooling fan control module is positioned at the front of the vehicle, adjacent to the radiator (in this shot it is shown from underneath the car). Check the unit for secure installation and sound electrical connections/wiring.

12

Attached to the bonnet catch on the car’s front panel is this electrical switch/wiring which signals to the ECU whether the bonnet is open or closed. Check that the unit is secure and that the cables/connections are sound.

13

The earth cable connection from the battery and negative jump-start connection point is hidden away at the rear of the engine bay. The connection point can suffer from corrosion, so dismantle the joint, clean and reassemble it (see Fault 4).

14

The screenwash jets have built-in heater elements to avoid problems of freezing. To help ensure reliable operation when you really need them, inspect the wiring and connections.

15

At the right-hand end of the fascia assembly is a plastic cover panel, which can be unclipped at its top edge and hinged downwards to reveal the car’s diagnostic socket. Dust can collect within it, so ensure this area is kept clear of debris.

16

This photograph shows the Snap-on Verus Pro diagnostic tool in action. The screenshot indicates that the coded 11th digit of the VIN (vehicle identification number) tells the operator the year in which the vehicle was built.

17

With the Verus Pro connected for electronic interrogation via the fascia-mounted diagnostic socket, this screenshot confirmed that no codes were stored in the ECU.