U010A–U010B Lost Communication With Exhaust Gas Recirculation 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 |
|---|---|---|
U010A | Lost Communication With Exhaust Gas Recirculation Control Module A | Investigate soon |
U010B | Lost Communication With Exhaust Gas Recirculation Control Module B | Investigate soon |
The definition
U010A: Lost Communication With Exhaust Gas Recirculation Control Module A.
U010A 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
The official definition is "Lost Communication With Exhaust Gas Recirculation Control Module A", and it comes from the industry-wide code list rather than from VAG. That matters here, because VAG's own fault-code tables contain no EGR control module at all. On these engines the EGR valve is driven straight from the engine ECU, and the faults VAG defines around it are circuit and system faults - EGR control circuit low, EGR control circuit high, exhaust gas recirculation system, EGR cooler changeover valve - never a lost-communication-with-a-module fault. So on a VAG this wording should be treated as a lead to be confirmed, not a verdict. Where something genuine sits behind it, it is describing a communication or supply problem at a device, not a mechanical one.
Most likely causes, in order
- Confirm the code before you act on it. The car reports a fault number; the words you read are whatever your tool's lookup table prints against that number. A basic reader falls back to the nearest generic description, which can name a module your car has never had. Have the car scanned with a tool that reads VAG's own fault text, tells you which module stored it, and gives you the freeze-frame conditions - then work from that wording instead of this one.
- Low system voltage. The cheapest thing to rule out. A tired battery or a charging fault makes devices drop out momentarily and log communication faults. If there are other unrelated communication codes stored across the car, test the battery and charging system before touching anything on the engine.
- Supply or earth fault to the device. A blown fuse or a corroded earth makes a healthy component look dead. Check the relevant fuse and the earth points in that part of the engine bay before assuming a part is at fault.
- Connector or wiring damage at the valve. The EGR area is hot, oily and vibrates constantly. Look for melted or hardened insulation, chafe where the loom crosses the engine, a plug that isn't fully clipped home, and green or corroded pins. A plug that has been off during other work is a prime suspect.
Worth knowing: This is a communication fault, not a blocked-valve fault. Cleaning or replacing an EGR valve for carbon build-up will not fix a code that says a unit cannot be heard, and a lot of money gets spent that way. If the car also has a genuine EGR flow, position or circuit fault stored in the engine ECU's own words, that is the one to chase - and that is a different code with different advice.
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 U010A mean?
U010A means Lost Communication With Exhaust Gas Recirculation Control Module A. This module has stopped talking on the car's data network, so nothing else can hear it.
Can I drive with U010A?
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.