Diesel Particle Filter (DPF): Testing and Inspection

Diesel Particle Filter Service Instructions


Complaint:
The customer complains about the Check Control message "Diesel particle filter malfunction".
The following fault codes are saved (one or more):
- 480A / 245700 (from F01) DDE: Diesel particle filter - filter is heavily contaminated. (exhaust backpressure is too high)
- 481A / 245800 (from F01) DDE: Diesel particle filter - filter is heavily contaminated. (exhaust backpressure is above maximum)

Cause:
The diesel particle filter is overladen. Regeneration of the diesel particle filter is being prevented by the DDE. The following cases can arise:
I. On the 325d and 525d with engine M57TUE:
unfavorable DDE software. The following integration levels are required:
- 325D E89x-09-12-512 or higher
- 525D E60x-09-12-512 or higher

II. The diesel particle filter is clogged due the recent driving profile.
Frequent short-distance drives and urban driving cause the diesel particle filter regeneration function to work less efficiently. Longer, extended and insufficient regeneration triggers the fault entry 480A / 245700 (from F01). As soon as the fault is saved, regeneration is then no longer possible. This function is inhibited.
If the diesel particle filter does not regenerate itself continuously, and if the exhaust backpressure continues to rise, the entry 481A / 245800 (from F01) is also made in the fault memory. The Check Control message "Diesel particle filter malfunction" appears on screen.

III. Engine fault
- other additional engine faults are also present

Measure:
I. On the 325d and the 525d M57TUE:
- Ensure that the vehicle is programmed with the following integration levels, otherwise update the integration level:
- 325D E89x-09-12-512 or higher
- 525D E60x-09-12-512 or higher

II. Perform a vehicle test and all relevant procedures. In the DDE, no relevant fault codes are allowed to be saved to memory, with the exception of 480A / 245700 (from F01) and 481A / 245800 (from F01).
First correct the existing faults.
Relevant fault codes are faults from the following areas:
- Charge air system
- Exhaust system
- Sensors (exhaust backpressure sensor, exhaust-gas temperature sensor)

NOTE: it is possible that the customer, in the light of the Check Control message, may visit the workshop and that the system may already have regenerated itself (e.g.: through an extended motorway journey). The customer is now aware of this process occurring. Check if the status of the fault is set to "Currently not present", then clear the fault memory.

III. Distance driven since last successful regeneration
IV. Carry out the procedures for fault codes 480A / 245700 (from F01) and 481A / 245800 (from F01), carry out the exhaust emissions check and keep a record of the exhaust backpressure figures.
V. Request regeneration using the service function.

NOTE: Regeneration is blocked by fault codes 480A / 245700 (from F01) and 481A / 245800 (from F01). Regeneration does not take place until the faults have been rectified by an extended regeneration drive (refer to chapter on regeneration)

VI. Carry out a regeneration drive
Once faults 480A / 245700 (from F01) and 481A / 245800 (from F01) have been saved, drive the vehicle for about 45 minutes at a constant speed. In addition, switch on electrical consumers to keep the exhaust-gas temperature between 280-350°C. That enables continuous regeneration to take place, the exhaust backpressure drops, the faults are remedied and the following status message is issued: "currently not present". Now, normal regeneration takes place automatically.

VII. Establish the distance driven since the last regeneration and check to find out if periodic regeneration has taken place. This status message is used to confirm successful regeneration.
VIII. Carry out another exhaust backpressure test with the diagnosis system. The exhaust backpressure must match the nominal values. If it does not, carry out the following checks:
- check the charge air system
1. check pipe connections for leak tightness
2. check charge air hose for tightness (leaks)
3. perform air mass system test
4. carry out function check of swirl flaps and exhaust-gas recirculation valve

- Check exhaust emission system:
1. Check exhaust backpressure hose to diesel particle filter for tightness and damage
2. Check exhaust sensors: check plausibility of temperature sensors and check the exhaust backpressure sensor

Regeneration
There are two kinds of regeneration:
1. Continuous regeneration:
This form of regeneration takes place during normal driving. At exhaust-gas temperatures of between 280-350°C, continuous regeneration takes place in the form of a slow oxidation process. The soot particles cannot be incinerated until the exhaust gases reach the required temperature.

2. Periodic regeneration:
Periodic regeneration is performed automatically by the DDE after no later than 100 km (600 miles). On vehicles with many short-distance drives, periodic regeneration already starts taking place after just 400 - 800 km (250 - 500 miles).
For regeneration, the intake air is reduced by the throttle valve. One or two post-injections are performed. This increases the exhaust-gas temperature to about 600 °C. The soot is incinerated with the residual oxygen.
The periodic regeneration is performed at all speeds. The most efficient method is regeneration at a constant speed in excess of 60 km/h (38 mph) over a period of 20-30 minutes.
The DDE calculates the time for periodic regeneration from the following values:
- average distance travelled
- average driving speed
- temperature in the diesel particle filter
- values from the exhaust backpressure sensor

The last successful regeneration can be read out by the diagnosis system

The following conditions must be fulfilled for a regeneration:
- the engine temperature must be in excess of 75 °C
- the exhaust-gas temperature before the diesel particle filter must be greater than 240 °C
- there must be enough fuel (fuel reserve lamp does not light up). Whenever the reserve lamp lights up, the regeneration process is suspended.
- No fault codes from the air system, exhaust emission system and sensors must be saved in the DDE
- The fault codes 480A / 245700 (from F01) and 481A / 245800 (from F01) must display the status "currently not present"
- Constant driving speed above about 60 km/h (approx. 38 mph). The optimum speed is about 100 km/h (approx. 60 mph).