Fuel System - MIL ON/DTC P03XX (Misfire)

Date: February 6, 2002

Order No.: P-B-47.10/23

Supersedes:

Group: 47

SUBJECT:
E-Class (W210)

Engine Performance / Check Engine Light with Code(s) P03xx

If you encounter instances in E-Class vehicles (W210) of engine misfire/lack of performance with low fuel level (below approx. 1/4) and/or "Check Engine Light" activated with code(s) P03XX (misfire detection), perform the following procedure.

Possible Cause:





Lack of fuel supply due to obstructed fuel supply opening to fuel pump in splash bowl. If tank level at time of misfire detection was low (below approximately 1/4), it is possible that the above described condition was caused by lack of fuel entering the splash bowl failing to feed the fuel pump due to foreign material blocking the fuel supply hole (Figure 1) (wit low fuel level, fuel enters only through supply hole at bottom of splash bowl).

Proceed as follows:

1. Ensure all related systems are working and within specifications - repair as necessary.

2. Check freeze frame for "fuel tank level", document freeze frame data and clear OBD memory.

3. Lower fuel level in fuel tank to approx. same level or lower than indicated in freeze frame.

4. Try to duplicate condition (load & RPM) as indicated on freeze frame and observe if engine misfires and/or misfire code is set.

5. Connect fuel pressure gauge and drive with high load/RPM and monitor fuel pressure. Fuel pressure should remain constant.

Note:

- Make sure codes are stored with fuel level � or below (see freeze frame data) ,i.e. below top of upper splash bowl rim, and no fuel can enter the splash bowl from top opening.

- If misfire can be duplicated and/or misfire code(s) are set again during procedure in step 4 and 5 or fuel pressure starts to fluctuate during procedure in step 4, replace fuel tank.

- If, during procedure in step 4 no misfire is observed and/or no misfire code is set, and the fuel pressure remains stable during procedure in step 5, the cause for the customer complaint is other than described above and needs to be further diagnosed.