Repair and diagnostics of Bosch starters for VW, Audi, Skoda
Repair and diagnostics of Bosch starters for VW, Audi, Skoda

Repair and diagnostics of Bosch starters for VW, Audi, Skoda

In this review, we will consider the main malfunctions, problematic parts and repair methods for the Bosch starter with the catalog number 02M911023P. The starter is installed on popular cars of the VAG alliance—Audi, Seat, Škoda Superb, VW Passat, VW Golf with 1.6-2.0 liter engines.

What motors are equipped with the Bosch starter 02M911023P


The German Bosch starter with the catalog number 02M911023P was installed from the factory on engines with a volume of 1.4 to 2.0 liters on cars of the VAG concern. These engines are ALZ, ALT, BFB, BPJ, AWT, EA 827, EA 188 and a number of other units of Audi, Skoda, Volkswagen and Seat.

стартер Bosch BOSCH 02M911023P

The Bosch 02M911023P starter is an original unit (OEM), its price for 2023 is approximately $250. However, there are analogues that are slightly cheaper, but similar in design and parameters. The most worthy owners of VAG cars consider:

  • Valeo 438226;
  • Cargo 113841;
  • Krauf STB1323;
  • Borg&beck BST2226;
  • Magneti Marelli 063521230140.

Their price is usually slightly lower than the original, but all the spare parts we will talk about are interchangeable.

Design of the starter Bosch 02M911023P


It is worth noting the first and main difference between the original Bosch starter and previous models of the 2000s. The modernized starter is unsupported. That is, earlier the starter housing was attached to the gearbox crankcase, and its shaft was supported by a brass sleeve in the gearbox crankcase.

стартер Bosch BOSCH 02M911023P
Supported and unsupported VAG starters

This led to the fact that the bushing wore out and the shaft got backlash. In some places, the starter gear could not engage with the engine flywheel. Thus, the starter could rotate idle without moving the engine flywheel. In the unit Bosch 02M911023P and its analogues this error was corrected, the starter became unsupported.

стартер бош

Its basic parameters:

  • voltage 12 В;
  • power 1.7 кВт;
  • number of teeth on the gear — 9 or 10;
  • number of mounting holes — 2;
  • direction of rotation – counterclockwise (CCW).

In general, the VAG starter has a classic design—it is a 4-pole DC motor, which is powered exclusively by a battery. Like most reduction starters, the Bosch 02M911023P starter consists of:

  • housing with stator winding;
  • rotor shaft anchor with rotor winding and radial commutator;
  • solenoid, which closes the contacts and supplies power to the electric motor itself, and also shifts the overrunning clutch (bendix) to transmit torque to the flywheel;
  • gear units;
  • roller clutch;
  • brushes that are located on the back of the housing and feed the radial commutator and start the electric motor.

In general, the design of the Bosch 02M911023P starter is simple, which allows you to make any repairs with your own hands.

starter design

Main faults of the starter VAG 02M911023P, symptoms


Depending on the symptoms of the malfunction, the following Bosch starter parts can be considered as potentially vulnerable:

  1. Brush pack. If you hear distinct clicks when starting the engine, the problem may be either in the brush gear or in the solenoid. Worn or destroyed brushes do not supply power to the radial commutator, so the starter does not start. Alternatively, the starter may not develop the required speed, this is also a symptom of worn brushes.
    щітковий вузел
  2. Roller clutch. When you try to start the engine, the starter motor rotates, but the flywheel and crankshaft remain in place. You will also hear a characteristic creaking, clicking, crunching sound.
  3. Rotor winding, the armature. The most unpleasant situation is when all the listed symptoms relate to the armature. Only in a few cases repair is possible, and in other situations the rotor will have to be replaced.
  4. Solenoid. When you turn the key in the ignition nothing happens, you can not hear the solenoids click, the starter does not rotate. Silence.
    втягуюче реле

Repair, solutions to the problem with the Bosch starter


The easiest option is to replace a worn-out spare part with an original or analogue. But it is also the most expensive. Only complex repair of the starter by the hands of some service center will be more expensive. Moreover, it is much more expensive. However, there are some spare parts that usually cannot be restored. Here are some examples:

  • original Bosch roller clutch, catalog number 1006209793;
  • roller clutch ZEN ZN1619;
  • solenoid, 2339305337 BOSCH;
  • solenoid 235535RMFD CARGO;
  • редуктор CARGO, 235025;
  • starter brushes, ІКА, 0 1088 1;
  • brush gear — CARGO 232700;
  • needle bearing 8.4096.0 IKA.

Usually, repair of the spare part, if it is possible, at the service station will cost 70-80% of the price of the spare part. You can also consider buying a refurbished original starter (if the masters give a guarantee), or a used starter. In both cases, we cannot predict the service life of the unit in advance. If we do not replace worn parts ourselves.

Disassembling and defecting the VAG starter


Disassembling and defecting the Bosch starter is performed according to the following algorithm.

Unscrew the studs on the back of the housing.


Remove the complete electric motor.


Remove the stator and inspect the condition of the magnets and windings. If there is no mechanical damage, wipe it from the inside and leave it alone.

магніти статора

Inspect the brush gear. Wear of brushes should not be more than 30-40%, that is, not less than 7 mm. Also, there should be no traces of damage and overheating on the brushes. To remove the brush assembly, unscrew it from the back cover, remove the locking ring, the back cover.

щітковий вузол

Using a 17 mm socket (or any according to the size of the radial commutator) remove the brush gear.


Inspect the rotor, if there are no signs of damage, check the radial commutator for leakage.


To do this, one feeler of the multimeter (in the ringing mode) is placed on the shaft, the second probe touches each of the sectors of the commutator. If the radial commutator breaks through to the mass, the multimeter will signal about it.

перевірка колектора

Unscrew the pins of the solenoid and disconnect it from the housing. 

корпус стартера

Inspect the condition of the planetary gearbox.

редуктор стартера

If necessary, wash and lubricate it. There are special lubricants for closed planetary gears (Liqui Moly Thermoflex Spezialfett, Ravenol Arctic Green Crease AGG2, Castrol LMX Li-Komplexfett2, Molykote AG-650, Molykote-7514).

мастило для редуктора

Also clean and lubricate the rotor shaft gear and splines on the back of the rotor shaft.

шестерні стартера

Check the condition of the front needle bearing. Most likely it will need to be lubricated. If there are signs of severe wear, the bearing should be replaced.


The roller clutch is replaced if there were cases of idling of the starter. 


Assemble the starter in reverse order. And before installing it on the engine, check its functioning with a battery and wires with clamps. How to do it correctly, we figured out here.

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