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BMW engine management light on, rough running or will not rev up

POSTED 27 November 2022

BMW engine management light on, rough running or will not rev up

Affected Vehicles

BMW

E9X series (2006 - 2012) | M3 | MSS60

Symptoms

  1. Engine management light on
  2. Rough running
  3. Will not rev up

Various fault codes stored in the DME in relation to throttle body

Faults

2B1F Throttle valve sensor, bank 1 Engine - DME
2B20 Throttle valve sensor, bank 2 Engine - DME
2B21 Throttle valve actuator pre-drive check, bank 1 Engine - DME
2B22 Throttle valve actuator pre-drive check, bank 2 Engine - DME
2B23 Idle actuator governor monitoring, bank 1 Engine - DME
2B25 Throttle valve monitoring, bank 1 Engine - DME
2B26 Throttle valve monitoring, bank 2 Engine - DME
2B27 Throttle valves, test of return springs, bank 1 Engine - DME
2B27 Throttle valves, test of return springs, bank 2 Engine - DME

Possible Causes

1. Worn Plastic Gears

Gears Worn
 
Worn Gears
Gears Worn

2. Dry, loose or burnt soldered joints

Circuit Defective

Circuit Defective

 

Repair Steps

1. Carry out a functional check

Confirm the customer's complaint.

2. Carry out a quick test

Quick Test

Quick Test


3. Check the fault codes stored in the DME

DME Code

DME Code

4. If the fault is stored for one bank only i.e. Throttle body pre-drive check Bank 2 (2B22) start by swapping the throttle bodies over from Bank 2 to Bank 1 and vice-versa.

If the fault travels to Bank 1 then the cause will be the throttle motor itself. If swapping the Throttles over the fault code did not travel and change sides then the wiring would need to be checked and or repaired between the DME and the Throttle that is stored as faulty. If the wiring checks proved to be OK, then it would indicate a faulty DME but that is a very rare repair.

5. Strip the throttle down and check for wear in the plastic gears and also check for loose, dry or burnt soldered joints on the transistorsstrip the trstrip the throttle down and check for wear in the plastic gears and also check for loose, dry or burnt areas.

See Images In The Causes Section. The soldered joints can be cleaned and re-soldered. The plastic gears can be replaced but the replacement parts are not from BMW. Only a replacement throttle motor is available from BMW.

6. After the repair you must run the Throttle valve actuator test. The DME will run the motors from min to max positions and will learn the end stops.

To do this go in to DME >> Service functions >>Throttle valve group test >> System test Throttle valve actuator.
Group Test

Group Test

Actuator Commands

Actuator Commands

 

7. The car is fixed when the engine runs correctly and there are no Throttle related faults stored.


Tools Required

  • Small electrical tools for stripping the throttle body
  • Soldering iron and solder

Parts Required

  • Throttle body