P2149–P217D Fuel Injector Group B Supply Voltage Circuit/Open
The circuit is broken somewhere - a cut wire, a corroded pin or an unplugged connector means the signal never arrives.
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 |
|---|---|---|
P2149 | Fuel Injector Group B Supply Voltage Circuit/Open | Investigate soon |
P217D | Fuel Injector Group H Supply Voltage Circuit/Open | Investigate soon |
The definition
P2149: Fuel Injector Group B Supply Voltage Circuit/Open.
P2149 is a manufacturer-specific powertrain code (the engine or gearbox). Its meaning is set by the carmaker rather than by the SAE standard, so a generic OBD-II reader will often show it as an unknown code or misread it.
What to check first
Cheapest and fastest checks first:
- Check the connector is fully seated and the locking tab is engaged. A half-seated plug is the single most common cause of an open circuit.
- Back-probe the pins and check continuity from the part back to the module connector.
- Inspect for a pushed-back or corroded terminal - the wire looks fine but the pin has backed out of the housing.
What actually causes this on a VAG
Petrol injectors are fed a supply voltage and the ECU switches the earth side to fire each one. P2149 means the ECU cannot see that supply reaching the second group of injectors. How many cylinders "group B" covers depends entirely on the engine - commonly half of them, or one whole bank on a V engine - so check the wiring diagram for your engine rather than assuming. Those cylinders stop firing, so expect heavy shaking, a big drop in power and, if the misfire is severe enough, a flashing engine light. The engine will normally still start and run roughly; a complete refusal to fire points at something feeding all the injectors, not just group B.
Most likely causes, in order
- Blown fuse or a failed supply relay. Cheapest thing to check and a common cause. The relay feeding the injectors usually feeds the coils and other engine electrics too, so a good test is to swap it with a relay of the identical part number from elsewhere in the same box and see whether the fault moves. Check the corresponding fuse at the same time.
- Corroded or water-damaged connector or loom joint. On many VAG models the engine ECU and its main plugs sit in the plenum chamber under the windscreen, and blocked scuttle drains flood them. Lift the scuttle cover and look for standing water, damp plugs and green pins. Injector sub-loom plugs sitting under the intake also corrode and chafe. Fix the drain as well as the connector, or it will happen again.
- One shorted injector dragging the shared feed down. A single injector that has failed internally can pull the common supply low or blow its fuse repeatedly. Suspect it if a replaced fuse blows again straight away. Rather than fitting fuses until one survives, measure each injector's coil resistance with the plugs off and compare them - they should all read close to each other, and the odd one out is your suspect. On direct-injection engines the readings are very low and much less revealing, so on those a workshop is better placed to isolate it.
- ECU internal supply or driver fault. Rare, and last on the list. Worth noting because an ECU cannot simply be swapped in on a VAG - it needs coding and immobiliser matching, so it should only be reached once wiring, fuses, relays and injectors have all been proved.
Worth knowing: A flashing engine light means raw unburnt fuel is pouring into the catalytic converter, which will destroy it in minutes. Stop, switch off and have the car recovered rather than nursing it home or repeatedly cranking it - a replacement cat costs many times what a relay or a fuse does. One thing worth knowing before anyone starts swapping relays: on direct-injection engines (FSI, TFSI, TSI) the injectors are driven from a high-voltage stage generated inside the ECU rather than straight from a relay, so on those a supply fault leans towards the injector loom and the ECU's internal supply. The fuse and relay feeding the ECU are still the right first check, because they cost nothing - just do not expect a relay swap to be the answer as often as it would be on an older port-injection engine.
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 P2149 mean?
P2149 means Fuel Injector Group B Supply Voltage Circuit/Open. The circuit is broken somewhere - a cut wire, a corroded pin or an unplugged connector means the signal never arrives.
Can I drive with P2149?
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.