The injector supply circuit for one group of injectors is open. Expect a serious misfire or a dead bank.
P2146 — also written P2146, P 2146, 2146 — is the OBD-II code for fuel injector group 'a' supply voltage circuit open. Same code, same fix: this page covers every spelling of it.
P2146 is a fuel & air fault code, typically costing £90–£900 to put right in a UK garage.
What causes P2146?
- Blown injector fuse
- Broken supply wire or connector
- Failed ECU injector driver
- Water in the injector loom
How P2146 is fixed
- Check the injector fuse and supply voltage at each injector plug
- Repair the loom
- ECU repair if a driver has failed
P2146 repair cost in the UK
Most P2146 repairs land between £90–£900 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Can you drive with P2146?
No. Running on a dead bank damages the catalytic converter quickly.
Urgency: high.
What P2146 is telling you
Fuel and air codes come from the ECU comparing the fuelling it commanded against the pressure, flow or mixture it actually measured. When those numbers disagree beyond the allowed tolerance, the ECU backs off to a safe map and logs the code.
On P2146 specifically — fuel injector group 'a' supply voltage circuit open — the stored code records the moment that check failed, not the moment the part gave up. That gap is why two cars with the same code can need completely different repairs.
How P2146 is diagnosed properly
Each of the known causes is ruled in or out in cost order, cheapest and most likely first. On P2146 that means working through them like this:
- Blown injector fuse — confirmed with live data before any part is bought.
- Broken supply wire or connector — checked with the loom flexed and the engine warm, because a wiring fault that is intermittent when cold shows itself under heat and vibration.
- Failed ECU injector driver — checked for outstanding manufacturer updates before any hardware is touched.
- Water in the injector loom — checked with the loom flexed and the engine warm, because a wiring fault that is intermittent when cold shows itself under heat and vibration.
An hour of diagnostic time on P2146 routinely saves more than it costs, because the alternative is buying the most expensive part on that list and hoping.
The repairs that actually clear P2146
- Check the injector fuse and supply voltage at each injector plug
- Repair the loom
- ECU repair if a driver has failed
After the repair the code is cleared and the car is driven until the relevant readiness monitor completes, rather than handed back as soon as the light goes out. A code that has only been erased will come straight back on the next drive cycle.
What happens if P2146 is ignored
Leaving this one is the expensive choice. The protection strategy the ECU falls into is there to limit damage, and every mile driven with the fault active is a mile the engine or gearbox spends outside its designed operating window.
For reference, P2146 typically lands at £90–£900 all-in at an independent garage in the UK — main-dealer quotes for the same job usually sit above that.
Getting P2146 looked at
Bob's Mechanical Repairs is an independent garage in Birnam, Dunkeld, Perthshire, with 32 years of Bob's experience on the tools. If P2146 is showing on your car, bring the scan results with you — we will read the live data ourselves, tell you which of the causes above it actually is, and price the repair before any work starts.