U0412–U0413 Invalid Data Received From Battery Energy Control Module 'A'
The ECU has logged a fault on U0412. The definition below is the exact wording the standard uses for this code.
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 |
|---|---|---|
U0412 | Invalid Data Received From Battery Energy Control Module 'A' | Investigate soon |
U0413 | Invalid Data Received From Battery Energy Control Module 'B' | Investigate soon |
The definition
U0412: Invalid Data Received From Battery Energy Control Module 'A'.
U0412 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:
- Read the freeze-frame data stored with the fault - engine speed, load and temperature at the moment it logged tell you whether this happens cold, hot or under load.
- Check the connector at the part for corrosion, and that it is fully seated.
- Clear the code and see whether it returns, and under what conditions.
What actually causes this on a VAG
On these cars the negative battery lead carries a sensor - the battery monitoring control module, -J367- on most VAG models - built into the earth terminal clamp itself. It measures battery voltage, current and temperature and reports over a single LIN wire, and the energy management system uses that to work out state of charge, whether to allow start-stop, and how hard to run the alternator. U0412 means the figures arriving from that side of the system do not add up: the values are implausible or out of range, rather than simply missing, which is what separates it from a plain lost-communication fault. Typical symptoms are start-stop refusing to work, odd charging behaviour, and dashboard messages about electrical consumers being switched off. Note that on many VAG cars the sensor's own faults appear under VAG's own numbers instead - U1050 and U1051 for the battery monitoring control module - so expect to see those alongside.
Most likely causes, in order
- A tired, flat or wrong-specification battery. Start here, because it is the cheapest and the most common. A battery that has lost capacity, or a plain lead-acid battery fitted where an AGM was specified, behaves in ways the system cannot reconcile with what it expects. A proper battery test under load will show it far more reliably than a voltmeter reading.
- A battery that was changed but never adapted to the car. If a new battery went in and its capacity, technology and serial number were never coded to the vehicle, the system is comparing real readings against the wrong reference. This is a very common omission after a DIY or fast-fit battery change, it needs nothing but a scan tool that can run the adaptation, and it costs no parts.
- Damage or a poor connection at the negative clamp, its lead, or the body earth. The sensor is part of the earth clamp and has a fine signal lead that is easily damaged when the terminal is levered off or over-tightened. Corroded terminals, a loose clamp or a chafed lead all produce nonsense readings. Check the clamp, its little wire and the earth strap bolt on the body - and check whether anything has been bolted straight to the negative post (see below), because that alone will do it.
- Failure of the sensor, or an open LIN line to it. The sensor does eventually fail, and so does the single wire that carries its data. Both come last, once the battery, the adaptation and the connections have been checked and proven. If the sensor is replaced it has to be adapted to the vehicle, exactly like a new battery.
Worth knowing: Never charge, jump start or bolt an extra earth lead - dashcam, amplifier, trickle charger clamp - straight onto the battery's negative post. Doing so bridges the sensor, and current that bypasses it is current it cannot see; it is one of the most common reasons for a car reporting implausible battery data and losing start-stop. Use the manufacturer's designated jump-start and charging points: the positive lead to the battery positive or the marked positive point, and the negative lead to the designated body earth point, never the battery negative terminal.
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 U0412 mean?
U0412 means Invalid Data Received From Battery Energy Control Module 'A'. It is logged when the ECU sees this circuit outside its expected operating window.
Can I drive with U0412?
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.