There was a time when a diesel engine starting fault was fairly simple to investigate. This is not the case with the B6 Passat. The starting process is controlled entirely by the engine ECU and not the driver. The glow plug ‘glow period’ is precisely set by the engine ECU according to parameters that it measures. The throttle is not involved in starting so pressing the fuel pedal has no effect on starting. There are a number of things that might cause a diesel Passat not to start but most of these are common to any diesel car.

Has the engine lost its cam or crank timing signal. If it has it will start but it will take a few more churns than normal.

Has the lift pump or tandem pump failed? Without fuel the engine won’t start.

This page is dedicated to the peculiar electronics involved in B6 Passat starting.

(This does not include KESSY)

There is no ignition key as such, just a Fob containing an immobiliser code chip. This is not related to door opening or the battery in the fob.

The fob is pushed into a hole in the dash which I’ll call the Ignition socket. It has several positions;

0. The fob is just in the hole, not pushed. No power is on as a result of this.

1. The fob is pushed to position 1. This is the ‘Radio on or accessory’ position.

2. The fob is pushed to position 2. This is the ignition on position and the dashboard symbols come on.

3. The fob is pushed to position 3. This is ‘Engine start’ position and the starter motor turns.

*Position 3 is spring loaded so when you stop pushing, the fob springs back to position 4.

4. Position 4 is really position 2 except the engine is now running.

If VW had left things like this, starting the car and investigating non-starting would be just like a traditional diesel car.

No radio function at position 1 would probably be a blown fuse.

No ignition at position 2 would probably be a faulty relay.

No starter action at position 3 would probably be a faulty relay or starter solenoid.

Unfortunately the Passat B6 designers made this system much more complicated. In fact the system is so complicated and involves so many electronic control units that fault finding can only be done using the dealer tools or a tool like VCDS. Some elements of repair cannot be done by any aftermarket tool and must be performed by VW dealers.

So if the engine won’t turn over on the starter motor, you need a diagnostic check. Not just a code read with a code reader, but a full read out of all self diagnostics. VCDS calls this an ‘autoscan’ to look for faults like these;

If the engine turns over on the starter motor but won’t start, you need a diagnostic check. Not just a code read with a code reader, but a full read out of all self diagnostics. VCDS calls this an ‘autoscan’ to look for faults like these;

If the engine won’t start you don’t really need these codes because it will be obvious if terminal 15 is staying off, the dash symbols won’t light up with ignition or start.


Below are just some of the codes that might show up to warn you of starting failure due to steering column lock problems.

They usually show up in; Address 25: Immobilizer

Sometimes no codes show at all.

Looking at the diagram below you can see that the wiring between the various components is pretty complicated but that is actually the simple bit. Wires can be examined and tested but the control units can’t, which is why you need the ‘autoscan’. The difficult bit is the CAN-bus communication. Several of the control units below are in communication with each other via the CAN wires. If they don’t receive the correct communications, they won’t function. This is something you cannot test so you have to hope it shows up in the ‘autoscan’.

These are codes telling you that the CAN system is not communicating correctly.



Communication between Electronic Steering Column Lock and electrical ignition

Communication between Electronic Steering Column Lock and Comfort System

Here is a VCDS scan result for a faulty steering lock;

Address 01: Engine Labels: 03G-906-016-BKC.lbl

Part No SW: 03G 906 021 DP HW: 028 101 274 2

Component: R4 1,9L EDC 000SG 7870

Revision: --H01--- Serial number: VWZCZ000000000

Coding: 0000071

Shop #: WSC 05314 000 00000


1 Fault Found:

005488 - Engine Start Blocked by Immobilizer

P1570 - 000 - - Intermittent

Freeze Frame:

Fault Status: 00100000

Fault Priority: 0

Fault Frequency: 2

Mileage: 213117 km

Time Indication: 0



Freeze Frame:

RPM: 1008 /min

Speed: 0.0 km/h

Load: 0.0 %

Voltage: 11.55 V

Bin. Bits: 11000100

Bin. Bits: 11000000

(no units): 1.0

Readiness: 0 0 0 0 0


Address 16: Steering wheel

Cannot be reached


Address 25: Immobilizer Labels: 3C0-959-433-25.clb

Part No SW: 3C0 959 433 AB HW: 3C0 959 433 AB

Component: IMMO 043 0383

Revision: 00043000 Serial number: VWZCZ000000000

Shop #: WSC 00449 210 82595


Part No: 3C0 905 861 C

Component: ELV 023 0350

3C0905861C ELV 023 0350

2 Faults Found:

02823 - Requirements for Locking the Steering Column Lock not met

000 - - - Intermittent

Freeze Frame:

Fault Status: 00100000

Fault Priority: 7

Fault Frequency: 3

Reset counter: 79

Mileage: 213117 km

Time Indication: 0



02861 - Electronic Steering Column Lock Check Sum Error

008 - Implausible Signal - Intermittent

Freeze Frame:

Fault Status: 00101000

Fault Priority: 4

Fault Frequency: 6

Reset counter: 78

Mileage: 212466 km

Time Indication: 0



If you have never disturbed the wiring or control units, they are probably ok. Electronic control units are pretty reliable these days.

Moving parts are far more likely to be a problem. The Ignition fob socket and the steering lock unit both contain moving parts.


Mechanical problems with this are usually obvious because the key fob won’t stay in the socket. Try another key to see if the main key is worn. If this doesn’t work, the socket probably needs replacing.


The picture above shows the position of the steering lock on the steering column.

The steering lock contains a small motor to release the steering column lock catch. It is a common failure on B6 Passats.


The picture below shows the Electronic Steering Column Lock with the motor and gear wheel removed.

I am using this picture to explain how the lock works.

I have marked two micro switches as ‘A’ and ‘B’. (‘B’ is part hidden by the lock frame.)

The two lock peg switch actuators are marked ‘a’ and ‘b’. (‘a’ is mostly hidden by the metal frame.)

The picture shows the lock in the process of being unlocked. At this stage it is mechanically unlocked but the car doesn’t know that for sure.