OBD-II trouble code
P2146: Fuel Injector Group "A" Supply Voltage Circuit/Open
This is not an injector code. It says the shared positive feed that several injectors run from has gone open, so all of them stopped at once. The cylinders that quit together tell you which ones share that feed — information no generic chart can give you, and the reason the misfire codes beside this one are worth more than the code itself.
Quick facts
- System
- Powertrain
- Category
- Fuel Injectors
- Severity
- High severity
- Drivable
- No — stop driving until repaired
- Repair cost range
- $20 – $700
- DIY difficulty
- Intermediate DIY
Browse every code in P2100–P2199, or start from the full code library.
What does P2146 mean?
The single most important thing to understand about P2146 is what it is not. It is not a report that an injector has failed. It is a report about a wire that several injectors share, and getting that distinction right is the difference between a fifteen-dollar repair and a bill for a set of injectors that were never broken.
Fuel injectors are two-wire devices. One wire is a positive supply, common to a group of injectors and fed from a relay or a fused circuit. The other is an individual control wire that runs back to its own driver inside the engine control module, which switches the injector on by completing the ground path. The module therefore owns the control side and merely monitors the supply side. When it monitors that supply and finds no voltage where there should be battery voltage, it sets a supply voltage circuit open code — and the letter in the code is the manufacturer's name for one particular supply branch, not a reference to a cylinder.
That architecture produces the most useful diagnostic property this code has, and it comes for free in the same scan. Losing a shared feed kills every injector on it in the same instant, and the module's misfire monitor notices each of those cylinders separately. So the cylinder misfire codes stored alongside P2146 are a direct readout of which cylinders belong to group A on this specific engine. There is no need to guess, and no need to trust a generic table, because the car has just told you.
That matters because the grouping itself is not standardised. Different manufacturers split injector supplies along different lines. Some feed one bank of a V engine from each branch. Some alternate odd and even cylinders. Some split an inline six into a front three and a rear three. Some pair cylinders by firing order so that no two members of a group fire consecutively. A generic listing that claims group A means particular cylinder numbers is describing one family of engines and quietly misleading everybody else. The misfire pattern, by contrast, is always right about the car in front of you.
Because the feed is common, the presentation is loud rather than subtle. On an engine with two supply branches, losing one leaves the other running, so the car shakes badly, has a fraction of its power and may still limp. On an engine where group A feeds every injector, an open feed is a no-start: the engine cranks normally, has spark and compression, and simply never fires because nothing is delivering fuel. That second case is often misdiagnosed as a fuel pump, because the symptom is identical from the driver's seat, and a pressure test at the rail will read correct while the engine refuses to start.
Where the open actually lives is usually upstream and usually cheap. The supply passes through a fuse and a relay before it ever reaches the harness, and either can fail. From there it runs to a splice point, and on many engines that splice is inside the loom on top of the engine, where heat cycling for a decade eventually loosens it. Only after that does it branch to the individual injector connectors. A fuse takes seconds to check and a relay can be swapped with its neighbour to test it, so the order of work should follow the circuit from the source outward rather than starting at the injectors and working back.
One caution on parts. If a shop has already replaced injectors on this code and the fault remains, that is not evidence of a stubborn problem — it is evidence the diagnosis started in the wrong place. A group supply fault sits upstream of every injector it feeds, so replacing all of them changes nothing at all.
Common causes
- Blown fuse in the injector supply circuit
- Failed injector or main power relay, or a relay socket with a burnt terminal
- Open splice inside the engine harness where the shared supply branches to each injector
- Corroded or melted supply terminal at one of the injector connectors on the group
- Broken conductor in the supply wire where the harness flexes over the engine
- Connector left unmated after injector, intake manifold or valve cover work
- Rodent damage to the injector harness, which sits in an easy place to reach
- Harness melted against the exhaust manifold, turbo housing or a hot casting
- Poor previous repair, such as a crimp splice that has pulled apart inside heat-shrink
- Open in the feed path inside the module where it sources the supply, which is uncommon
Symptoms
- Engine cranks strongly but will not start, with fuel pressure reading normal at the rail
- Engine starts and runs on only part of its cylinders, shaking heavily with very little power
- Multiple cylinder misfire codes stored in the same scan, always the same set of cylinders
- Check engine light on, often flashing, with a lean bank code alongside
- Strong fuel smell absent, because the affected injectors are not spraying at all
- Complete loss of power when the fault comes and goes while driving
- Backfiring or popping on deceleration where unburnt air passes through the affected cylinders
- Fault appeared immediately after work that required the injector harness to be moved
- No change in behaviour after replacing injectors or the fuel pump
- Symptoms that come and go with engine bay temperature or with a bump in the road
Diagnostic steps
- 1.Read every stored code before touching anything, and write down which cylinders have misfire codes. That list is the map of which cylinders share group A on this engine, and it is more useful than any generic chart.
- 2.Check the injector supply fuse and the relay that feeds it first. They are upstream of everything else, they are the cheapest possible cause, and a relay can often be proved by swapping it with an identical one nearby.
- 3.Back-probe the supply terminal at one injector on the affected group with the key on and confirm whether battery voltage is present. No voltage there and voltage at the fuse means the open is between them.
- 4.Work outward from the source rather than inward from the injectors. Confirm voltage at the relay output, then at the harness splice, then at each connector, so the open is bracketed rather than hunted.
- 5.Locate the splice point where the common supply branches. On many engines it sits inside the loom above the engine and is the single most likely place for an open after a decade of heat cycling.
- 6.Voltage-drop test the supply under load rather than relying on a static reading, because a badly corroded but still connected joint can read battery voltage with no current flowing.
- 7.Inspect the harness where it crosses or rests near the exhaust manifold, turbocharger or any hot casting, and flex each suspect section while watching the meter.
- 8.Check the injector connectors on the affected group for melted or pushed-out supply terminals, and drag-test each pin instead of judging contact by appearance.
- 9.Do not condemn injectors on this code. Prove the supply is present and correct at every affected connector first; only then does injector testing mean anything.
- 10.After the repair, clear the codes and confirm the misfire codes stay away under load as well as at idle, since a marginal joint can carry idle current and fail at higher demand.
Repair cost
$20 – $700
The range is wide because the fault can sit anywhere along one wire. A blown fuse is a couple of dollars and a relay is $15 to $60 with minutes of labour, which is genuinely where a good share of these end. Diagnosis is $110 to $250 and is the honest cost, because finding an open in a shared feed is tracing work rather than parts swapping. A harness or splice repair runs $120 to $450 depending on how deeply the damaged section is buried under loom. A connector or terminal repair at an injector is $90 to $220. Replacing injectors on this code costs $400 to $1,200 and fixes nothing, which is exactly why the diagnostic order in this page starts at the fuse.
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DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.