VW Bug Info

FAULT:
Engine doesn't start or stalls briefly after the start - ECU disabled
CAUSE:
The ECU is intermittently disabled Because of a fault in the immobiliser (transponder).Due to corrosion
on the connectors of the immobiliser control unit there are often loose connections.
SOLUTION:
If the immobiliser control unit has no fault stored, the cause is a loose contact or an excessive
transition resistance on connectors or earth connection.
· Check the earth cable and earth contact for the immobiliser control unit.
· The cables of the control unit must be routed free of tension.
· With height adjustable steering wheels make sure the cable to the reading coil has enough clearance. Observe
the maximum adjustment range of the steering wheel.
· Attach the loose cable from the reading coil with a cable binder at a suitable point, as near to the control unit
as possible.

In case of persistent complaints replace both control unit and reading coil with tin-plated contacts or with
gold-plated contacts. A mixed installation of tin-plated and gold-plated contacts is causes corrosion.
· The old part number of the control unit is indicated using the V.A.G 1551
· For identification the new control unit has a brown mark or the plug end is brown.

GLOW WARNING FLASHES PERMANENTLY
FAULT:
Diesel engine, Glow warning flashes permanently, Starting problems, fault entry 17978 engine starts and
stalls again straight away. Restart is possible.
CAUSE:
It is intermittently not possible to read the key signal because of a software or hardware fault in the
combination instrument of the supplier Magneti Marelli. The V.A.G tester indicates the fault "Key, signal too small".
On vehicles with TDI engine the glow warning flashes permanently. This is caused by a software fault in the ECU.
SOLUTION:
Replace the parts, Modified combination instruments have the same part number, but are a new data
version. Display in the V.A.G tester - Part No. 3B0 919 ... .. V06. Check and repair according to the Workshop
Manual. If no fault is found, delete the fault memory and avoid repairs.

ENGINE DIFFICULT TO START WHEN WARM
AFFECTED MODELS:
1.9L TDI 181 KW only with manual gearbox engine code AFN.
FAULT :
Engine difficult to start when warm, only after approx. 20 seconds of starter operation.
CAUSE:
The starter motor is not revving fast enough.
SOLUTION :
Check the battery. If no fault is found, carry out a test by programming the ECU to automatic gearbox. If the engine then starts normally, replace the starter motor. After replacing the ECU recode to manual gearbox.
ENGINE DOESN'T START OCCASIONALLY
FAULT:
Engine doesn't start occasionally, frequently after a short drive, the ECU is locked
CAUSE :
The electrical system collapses in jerks when engaging the starter motor. As a result the ECU is locked. Only model year 96 with 44 Ah battery affected. SOLUTION:
Check the earth cable from battery to engine and particularly the earth pin on the body below the battery is properly installed.
FLUCTUATING, EXCESSIVE IDLE SPEED
AFFECTED MODELS:
All vehicles with Bosch Motronic fuel injection system.
FAULT:
Fluctuating, excessive idle speed - engine starts after charging the battery.
CAUSE:
If the battery is disconnected or discharged the Motronic control units lose their programmed and stored basic adjustments.
SOLUTION:
When starting the engine after the battery was discharged or disconnected, switch on the ignition for approx. 10 seconds and then switch it off again. This makes sure that the old adaptation values are deleted and stored again in the control unit. After this the engine starts without problems and the above symptoms do not occur again.
INCREASED IDLE SPEED
A FFECTED MODELS :
Model year 96 Magneti Marelli 1AV, 1.6L, AEE engine.
FAULT:
Increased idle speed (max. 2,500 rpm) after starting the engine with a coolant temperature between 18deg.C and 29.5deg.C
CAUSE :
Software problems lead to increased idle speed (max. 2,500 rpm) after starting the engine with a coolant temperature between 18deg.C and 29.5deg.C. After approx. 40 seconds or after the first acceleration the idle speed returns to normal.
SOLUTION:
Install the modified control unit:
Polo - Part No. 032 906 030 E
Polo Automatic - Part No. 032 906 030 H
Golf - Part No. 032 906 030 K
The control unit must be adapted to the electronic immobiliser. Also carry out a basic setting of the ECU (adapting it to the throttle valve control unit).