fault code guideHybrid & EV
U0293: Lost Communication With Hybrid/EV Powertrain Control Module
The car computer has lost contact with the hybrid or electric powertrain controller. Your car will usually refuse to start or enter READY mode until the connection is restored.
How it shows up: The engine management light and hybrid warning message appear on the dashboard, and the car fails to display the READY light. An OBD scanner will log code U0293 and fail to communicate with the hybrid control module.
Updated 10 November 2026
Can I keep driving?
Stop driving
The high-voltage drive system is disabled, meaning the vehicle cannot drive or may lose motive power without warning.
What to do right now
- 1Pull safely off the road or into a car park if the vehicle is still moving.
- 2Turn off the car and leave the high-voltage system alone, as orange-cabled parts are strictly for trained technicians only.
- 3Avoid repeated start attempts if warning messages flash on the instrument cluster.
- 4Arrange roadside assistance to recover the vehicle to a qualified specialist or main dealer.
Likely causes
Most likely first.
- Likely
Discharged or failing 12-volt auxiliary battery
Hybrids and electric vehicles rely on a standard 12-volt battery to boot up onboard computers before closing high-voltage contactors. If 12-volt power drops too low during startup, the hybrid controller cannot boot or broadcast over the network.
- Possible
Blown fuse or faulty power relay
The hybrid powertrain controller draws operating current through designated low-voltage fuses and main relays. A blown fuse cuts supply completely, making the module appear missing on the data network.
- Possible
CAN bus wiring or connector damage
Controller Area Network wires carry digital messages between controllers. A loose plug, moisture ingress or wiring damaged by rodents will interrupt this digital signal.
- Rare
Internal hybrid powertrain control module failure
Internal hardware failure or corrupted processor firmware prevents the controller from transmitting data. This typically requires module replacement or reprogramming.
What you can check yourself
Park somewhere safe and level, engine off, before you start.
- 1
Test the 12-volt auxiliary battery
Use a digital multimeter across the terminals of the 12-volt battery with the car switched off. A healthy battery should read at least 12.6 volts; anything below 12.0 volts can prevent hybrid computers from communicating.
- 2
Inspect low-voltage fuses
Consult the owner handbook to locate the auxiliary fuse box, then check the fuses protecting the hybrid control unit and powertrain systems. Replace any blown fuse with one of the exact same amp rating.
- 3
Check visible low-voltage wiring
Inspect the accessible 12-volt wiring looms around the fuse box and 12-volt battery for rodent chewing or loose earth points. Never touch, pull or inspect any bright orange cables, as high-voltage parts carry lethal current and are strictly for trained technicians only.
Rough cost to fix
Rough estimateTypical prices in Ireland (€) and the UK (£), from an independent garage up to a main dealer. The total bill depends on whether the issue is simply a depleted 12-volt auxiliary battery or a failed control module requiring dealer-level software programming.
12-volt auxiliary battery replacement
- Do it yourself
- €130–270£110–230 in the UK
- At a garage
- €190–380£160–330 in the UK
Low-voltage wiring or fuse circuit repair
- Do it yourself
- Garage job
- At a garage
- €150–400£130–350 in the UK
Hybrid powertrain control module replacement and programming
- Do it yourself
- Garage job
- At a garage
- €950–2,500£820–2,150 in the UK
When to go to a garage
- The 12-volt battery is fully charged and all low-voltage fuses are intact, but the car still refuses to go into READY mode.
- Diagnostics point towards high-voltage controllers or orange-cabled systems, which require specialised insulated tools and trained personnel.
- The vehicle lost drive power while on the road and displays hybrid system failure messages.
Questions drivers ask
Can I drive my car with fault code U0293 active?
In almost all cases you cannot drive at all because the vehicle will not enter READY mode. If the fault strikes while already driving, the vehicle may switch to a limp mode or cut high-voltage power completely, meaning you should pull over as soon as it is safe.
Why does a weak 12-volt battery cause hybrid communication codes?
Although hybrid cars have a large traction battery, the computers and safety relays run entirely on a conventional 12-volt circuit. When this auxiliary battery degrades, system voltage sags during power-up, causing the hybrid powertrain controller to crash before establishing communication.
Will disconnecting the 12-volt battery clear U0293 permanently?
Disconnecting the battery may wipe the stored code temporarily, but it will return the moment the car performs its network self-check. If an underlying wiring issue, blown fuse or hardware fault remains, the hybrid computer will stay unreachable.
Will code U0293 cause an NCT or MOT failure?
On the UK MOT, an illuminated engine management light is an automatic fail on qualifying vehicles, and an unstartable car cannot complete the test. On the Irish NCT, while an engine code alone gives an Advisory Pass, testers will abort the test if the car cannot be started and moved safely onto the test lanes.
Test rules here are for the National Car Test in Ireland (NCT) and the MOT in the UK. Elsewhere, check the regulations of your own country or state before going for a vehicle test.
The warning light you may see
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General guidance for most cars, not a diagnosis of yours. Details differ by make, model and year - check your handbook, and if in doubt, don't drive.