Repairing auxiliary coolant heater -B7W/D7W- — VW
Repairing auxiliary coolant heater -B7W/D7W- on VW: factory workshop procedure. Full factory text, tools and checks.
Workshop procedure for VW — the factory write-up, straight from real workshop data.
📋 Procedure
Repairing auxiliary coolant heater -B7W/D7W-
Caution
Before working on the auxiliary heater and/or the fuel system, pull out the appropriate fuses
Current flow diagrams, Electrical fault finding and Fitting locations
.
Note
B7W: Petrol electric water heater
D7W: Diesel electric water heater
A manufacturer's plate is attached to the heater unit. This plate gives details of the heater unit type installed in the vehicle
Fig.
.
Removing and installing heater unit components
Chapter
.
Check the coolant circuit after working on the coolant circuit
Rep. Gr.
19
.
Thermal switch F80
Opens at an engine coolant circuit temperature of 55°C.
Connects engine circuit to heater circuit via
coolant shut-off valve
N82
. Further notes
Chapter
.
Fresh air blower relay
J13
Behind dash panel, right.
Fresh air blower
V2
is switched to the 2nd stage when the coolant temperature in the heater circuit reaches 55°C.
Removing and installing
Chapter
.
Resistance wire relay
J116
Behind dash panel, right.
Protects
engine glow plugs
Q6
against excessive voltage when ignition is switched on.
Removing and installing
Chapter
.
Heater control unit
J162
Behind dash panel, right.
Removing and installing
Chapter
.
Pre-selection clock
E111
Removal
Chapter
.
Operation and function
Chapter
.
Note
The water heater can only be switched on when the temperature selection lever, on the heated air and fresh air controls, is pushed completely to the right.
Switch for control relay - heater regulating valve open
F102
On the heated air and fresh air controls.
Removing and installing
Chapter
.
Fuse carrier
Under driver's seat.
Fuse assignment
Chapter
.
Fuel pump
G23
Note
The B7W and D7W water heater fuel pumps have different fuel delivery rates: Note part number.
Removing and installing
Chapter
.
Checking fuel quantity delivered
Chapter
.
Exhaust system
Removing and installing
Chapter
.
Securing exhaust pipe to heater unit
Chapter
.
Heater unit
Removing and installing
Chapter
.
Dismantling and assembling
Chapter
.
Coolant distributor
With non-return valve.
Coolant hose routing
Chapter
.
Manufacturer's plate
Note
Only the 20168105 / 25171405 versions are factory-fitted in the Transporter 1991▸.
Water heaters with other version numbers are repaired by authorised Eberspächer workshops.
TorqFix answers live for your specific car — tell it the engine code and it serves the matching sequence, torque figures and wiring for that exact variant.
Ask about my car →Other VW procedures
- Removing engine · 41 torque figures
- Removing and installing camshaft – VW Golf Cabriolet · 47 torque figures
- Adjusting valve timing – VW Passat B5 · 83 torque figures
- Removing and installing camshafts – VW Passat B6 · 39 torque figures
- Removing and installing coolant pump · 53 torque figures
- Removing and installing brake master cylinder, left-hand drive
- Removing and installing supplementary heater · 1 torque figures
- Adjusting stop buffers – VW Passat B7 Variant · 2 torque figures
- Removing trim panel – VW Polo 6R · 1 torque figures
- Removing and installing engine bracket, Golf Plus
Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
The story behind TorqFix →Workshop data on this page last updated 20 Sep 2026.