U0166: Perte de communication avec le calculateur du chauffage additionnel
Que faire
The auxiliary heater will not run. If you rely on it for pre-heating on cold mornings, that is worth fixing before winter rather than after.
This is the small burner that runs on your own fuel to warm the engine or the cabin — the thing that lets the car be warm before you get in. Modern diesels produce so little waste heat on short journeys that many need one.
Two reasons it is worth more than comfort. The engine now starts cold every time, and cold starts are where most engine wear happens; on a diesel it also means more soot into the particulate filter. And if this heats a motorhome, a sleeper cab or a vehicle people work in, it is not a convenience at all.
One safety point. These heaters burn fuel and have their own exhaust, so they produce carbon monoxide. Never run one in a garage or any enclosed space, and if it is behaving unpredictably — starting when it should not, or refusing to stop — have it isolated rather than lived with.
Three cheap things to check first, before anyone quotes for the unit: its own fuse (it usually has a dedicated one), its fuel pump connector (under the vehicle, in the salt), and the fuel level — many of these refuse to run below a threshold so that they cannot empty the tank.
Ce que signifie ce code
The auxiliary heater control module has stopped being heard from. The general reasoning is at U0100, and U0425 covers the same module reporting implausibly instead.
An auxiliary heater is a small burner that runs on the vehicle's own fuel, heating the coolant or the cabin air directly. It exists because a modern diesel is efficient enough that it produces very little waste heat at idle and on short journeys — so on a cold morning the cabin, and often the engine, need heat the engine itself cannot supply. Many are programmable, so the vehicle can be warmed before anybody gets in.
When the module goes silent the heater simply does not run, which is a comfort problem in a temperate climate and a real one where it is not. Two consequences are worth naming.
On a vehicle used for pre-heating, the engine now starts cold every time. Cold starts are where most engine wear happens, and on a diesel a genuinely cold start also means poor combustion, more soot into the particulate filter, and a regeneration cycle that struggles — so an unfixed auxiliary heater has a downstream cost beyond a chilly cabin.
And where the heater warms the cabin of a vehicle people sleep or work in — a motorhome, a sleeper cab, a welfare vehicle — this is not a convenience at all.
One safety note that belongs on any page about a fuel-burning heater. These units have their own exhaust and produce carbon monoxide. A heater behaving unpredictably — running when it should not, or refusing to shut down — must not be left to it, and must never be operated in a garage or an enclosed space. If it runs at all while this fault is stored, treat that as a reason to isolate it rather than to live with it.
Where the fault usually is: the unit lives under the vehicle or in a wheel arch, with its own fuel line, its own pump and its own fuse. Water, salt and stone damage account for most of these, and the fuse and the fuel pump's connector are the cheap things to check first. Many also refuse to run below a fuel level threshold, which is worth ruling out before anything is dismantled.
Causes probables
Commencez ici
- Fusible grillé ou alimentation hors service · facile
- Connecteur corrodé ou mal enclenché · facile
- Faisceau de câblage endommagé · modérée
- Infiltration d'eau dans le connecteur du calculateur · modérée
Moins fréquent
Symptômes
Composants concernés
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