U010C–U010D Lost Communication With Turbocharger/Supercharger Control Module A
This module has stopped talking on the car's data network, so nothing else can hear it.
Can you drive it? The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.
Which code is which
Same fault, different cylinder or bank — diagnosed the same way. Several set together usually means one shared cause.
| Code | Definition | Severity |
|---|---|---|
U010C | Lost Communication With Turbocharger/Supercharger Control Module A | Investigate soon |
U010D | Lost Communication With Turbocharger/Supercharger Control Module B | Investigate soon |
The definition
U010C: Lost Communication With Turbocharger/Supercharger Control Module A.
U010C is a network code (communication between control modules), defined by the SAE standard - it means the same thing on any make of car, and any generic OBD-II reader will decode it.
What to check first
Cheapest and fastest checks first:
- Check power and earth at the module first - a module with no supply cannot answer.
- Check the two data-bus wires for continuity and for a short between them.
- Scan the other modules: if several report the same module missing, the fault is at that module rather than on the bus.
What actually causes this on a VAG
Many modern VAG turbo engines no longer use a plain vacuum can to control boost. The actuator on the turbo is an electronic unit that positions the wastegate or the vanes and reports its position back to the engine ECU. VAG treats it as a device in its own right and defines a cluster of faults around it - the turbocharger control module running too hot, its voltage supply going outside the permissible range, its position sensor going silent, and the actuator having been fitted but never adapted. U010C is the one that says the ECU has stopped hearing from it altogether. Expect reduced power or limp mode, sometimes intermittently, and often worse when the engine is hot.
Most likely causes, in order
- Wiring and connector at the actuator. Free to inspect and the first thing to look at. The actuator lives in the hottest, most vibration-exposed place on the engine. Look for insulation that has hardened or melted where the loom passes near the turbo or manifold, a plug that has worked loose, and corroded pins. Also check for damage after any recent work in that area, or water ingress after an engine bay wash.
- Supply, earth or fuse fault. A device with no power behaves exactly like a failed one. Check the relevant fuse and the earth points before condemning anything - VAG has a specific fault for this actuator's supply voltage being out of range, which tells you how routinely it happens.
- Weak battery or charging fault. Unstable voltage causes intermittent dropouts and communication faults across several systems at once. If other unrelated communication codes are stored alongside this one, start with the battery and charging system rather than the turbo.
- The actuator's own electronics failing with heat. The expensive end, so leave it until the cheap checks are done. Heat-soaked electronics sitting on a turbo are a known wear item, and VAG defines a fault for this control module simply getting too hot. The tell-tale is a fault that appears when the engine is hot and clears when it cools. Confirm it with live data - the position feedback will be missing or implausible - rather than by assumption.
Worth knowing: On many of these engines the electronic actuator can be replaced on its own rather than as part of a complete turbocharger, and the cost difference is large - so before agreeing to a whole turbo, ask specifically whether the actuator is available separately for your engine. Whichever way it goes, a new actuator has to be adapted to the turbo with a proper diagnostic tool afterwards; VAG stores a fault for an actuator that has been fitted and never adapted, so treat that step as part of the job rather than an optional extra. In the meantime, don't lean on it. A boost control system that isn't reporting its position properly is not something to drive hard on.
Reading the code is the easy part
A code names the circuit that complained. What tells you why is watching the sensor behind it while the engine runs — and that is where a code reader stops and a diagnostic tool starts.
VAGPULSE reads every module in a VW, Audi, Skoda or SEAT — not just the engine — shows the live measuring blocks behind this fault, gives you the freeze-frame conditions it was logged under, and clears it once you have fixed it. It also does what a generic OBD reader cannot on a VAG: service resets, coding, adaptations, and Stage 1–3 flashing with your original file saved first.
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Common questions
What does U010C mean?
U010C means Lost Communication With Turbocharger/Supercharger Control Module A. This module has stopped talking on the car's data network, so nothing else can hear it.
Can I drive with U010C?
The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.