Checking actuation of electric additional heater by engine control unit — AUDI
Checking actuation of electric additional heater by engine control unit on Audi: factory workshop procedure. Full factory text, tools and checks.
Workshop procedure for AUDI — the factory write-up, straight from real workshop data.
📋 Procedure
Checking actuation of electric additional heater by engine control unit
Note
The electric additional heater is activated by the engine control unit (control unit for the diesel direct injection and glow plug system) as soon as certain preconditions are met:
Relevant Workshop Manual, Diesel Direct Injection and Glow Plug System
The following values relating to the additional heater can be read out from the measured value block of the engine control unit for vehicles with diesel engines:
The ambient temperature is less than +5 ° C (transmitted by the
control unit in the dash panel insert
J285
).
The additional heater is switched on or off (
“Econ”
mode is not switched on and
“heat output”
requested with air conditioner)
The current coolant temperature
Relevant Workshop Manual, Diesel Direct Injection and Glow Plug System; Repair group 01
Different engine control unit versions are installed depending on the version of the
heating element for additional air heating
Z35
(900 or 1500 watts).
Relevant Workshop Manual, Diesel Direct Injection and Glow Plug System
and
Parts List
Depending on the version of the engine control unit used, if
“01”
is displayed in the measured value block, for example, on vehicles with an electric additional heater rated at 1500 watt capacity, this merely indicates that the additional heater is actuated. Heat output control of this additional heater is via the electronics installed in the
heating element for additional heater
Z35
(by evaluating the alternator load).
Relevant Workshop Manual, Diesel Direct Injection and Glow Plug System
On vehicles with a 1500 W
heating element for additional heater
Z35
, the alternator load is controlled by the
heating element for additional heater
Z35
in such a way that it is at approx. 90%. If the alternator load exceeds 95 % (e.g. due to switching on an additional electrical consumer), the
heating element for additional heater
Z35
automatically reduces the current consumption and, thus, the heat output.
Vehicles with a 900 watt
heating element for additional heater
Z35
are currently fitted with a 120 A
alternator
C
, whereas vehicles with a 1500 watt
heating element for additional heater
Z35
are currently fitted with a 140 A
alternator
C
.
Parts List
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.
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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.