OBD-II trouble code
P2047: Reductant Injector Circuit/Open (Bank 1 Unit 1)
This is the first DEF code in the range that is about an output rather than an input, and that changes everything about how it behaves — the module can set it at key-on, with the engine cold and before a single drop of fluid has moved.
Quick facts
- System
- Powertrain
- Category
- Exhaust / Aftertreatment
- Severity
- High severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $120 – $1,400
- DIY difficulty
- Advanced DIY
Browse every code in P2000–P20E8, or start from the full code library.
What does P2047 mean?
Every reductant fault numbered below this one concerns something the module reads. P2047 concerns something the module commands, and the distinction matters more than it sounds.
A sensor fault is discovered by judging a number: is this voltage plausible, does it agree with the other inputs, does it move when it should. An output fault is discovered differently. The reductant injector — the dosing valve, on many platforms — is a solenoid, and the module drives it directly. To check it, the module does not need a reading from anywhere; it can interrogate its own driver circuit. Most implementations push a very small current through the load while the valve is at rest, far too little to open it, and simply confirm that the current has somewhere to go. If it does not, the circuit is open. That check runs at key-on, which is why this code frequently appears with the engine barely warm and no dosing yet attempted. A driver who reports the light came on before they left the driveway is describing normal behaviour for this code, not an unusual case.
The second fact that separates this component from the rest of the DEF system is where it lives. The tank, the pump, the level sender and the temperature sensor are all in a cool, sheltered part of the vehicle. The injector is not. It is bolted directly to the exhaust, at the decomposition tube ahead of the SCR catalyst, in the hottest and most thermally violent location any DEF component occupies. Its coil is heat-soaked every time the engine runs and quenched by the fluid passing through it, its connector sits in radiant heat, and its pigtail bakes. So the population of failures here skews away from the chafed-wire story that dominates underbody sensor circuits and towards two specific things: a coil that has gone open from thermal cycling, and a connector or pigtail whose insulation has embrittled until a conductor parted inside it. Inspecting the harness by eye is worth less here than at the tank, because the damage is usually inside the insulation rather than through it.
The third is what the module does next, and it has no middle setting. With a temperature or pressure input missing, the module falls back on an assumption and keeps running on reduced information. With the injector circuit open there is nothing to fall back on: the actuator that puts reductant into the exhaust is not there, so dosing stops completely and NOx conversion goes to zero immediately. The downstream NOx sensor notices within a drive cycle, which is why this code so often arrives with company — efficiency and system performance codes stored alongside it are usually consequences rather than separate problems, and chasing them first wastes money.
One note on the address in the title. "Bank 1 Unit 1" is a position, not decoration. Most light and medium-duty installations use a single doser and will only ever report unit 1, but twin-bank and dual-dosing systems exist, particularly on larger engines and some heavy-duty aftertreatment layouts. On those, reading which unit the code names tells you which side of the exhaust to open before anything is lifted, and it is worth confirming rather than assuming there is only one.
Common causes
- Injector solenoid coil failed open from repeated heat cycling at the exhaust mount
- Pigtail or connector insulation embrittled by radiant heat, with a conductor parted inside it
- Connector unlatched, corroded or heat-damaged at the injector
- Open in the control or supply conductor between the module and the injector
- Terminal backed out or damaged at the injector connector
- Loss of the switched supply feeding the injector, including a failed relay or fuse on that circuit
- Corroded ground or connector interface at the reductant control module
- Injector replaced previously with the connector not fully seated
- Chafe through the harness section running along the exhaust or frame rail
- Reductant control module output driver failed open
Symptoms
- Check engine light appearing at or shortly after key-on, before the vehicle has been driven
- DEF or SCR warning message on the dash
- No DEF consumption over time, with the tank level effectively static
- Scan tool showing no injector current or duty when dosing should be commanded
- NOx efficiency or reductant system performance codes stored alongside
- Staged power or speed reduction as the inducement sequence advances
- Vehicle driving and starting normally otherwise
- Fault appearing after exhaust, DPF or aftertreatment work in the same area
- Emissions test failure or readiness monitors that will not complete
- Code returning immediately after a clear, rather than after a drive cycle
Diagnostic steps
- 1.Note when the light appeared. A code that sets at key-on with no dosing attempted is consistent with the module's resting circuit check and points at continuity rather than at fluid delivery.
- 2.Confirm which unit the code names before lifting the vehicle. Single-doser systems always report unit 1, but dual-dosing layouts exist and the address tells you which side to open.
- 3.Command the injector with a bidirectional scan tool and watch for current flow. No current with the command active confirms an open rather than a delivery problem.
- 4.Unplug the injector and measure coil resistance directly at its pins, comparing against the service figure. An open coil settles the diagnosis at the component without further harness work.
- 5.Check for the switched supply at the injector connector with the key on, then check the control side back to the module. Losing the feed produces the same code as losing the coil.
- 6.Flex the pigtail and the first few inches of harness while measuring, since heat-embrittled insulation hides a parted conductor that looks perfectly sound.
- 7.Inspect the connector for heat distortion, discoloured terminals and melted locking tabs. This connector's environment is far harsher than anything at the DEF tank.
- 8.Test the control conductor from the module end to the injector end for continuity, and check the module's ground and supply before condemning the driver.
- 9.Read the companion codes rather than clearing them. NOx efficiency and system performance faults stored with this one are usually downstream effects of dosing having stopped.
- 10.After repair, verify the injector actually meters fluid rather than just passing a circuit test, then confirm DEF consumption resumes and the conversion efficiency recovers over a full drive cycle.
Repair cost
$120 – $1,400
Diagnosis is $120 to $250. A connector, pigtail or harness repair is $100 to $450 and is a common outcome given the heat this area sees. Replacing the injector itself is the usual parts-level result: $180 to $900 depending on platform, with light-duty dosers at the low end and heavy-duty units at the top, plus 0.5 to 2.5 hours of labour. Labour climbs when mounting studs have seized into the exhaust flange or when heat shields and other aftertreatment components have to come off for access, which is common on higher-mileage vehicles. If the decomposition tube has to be cleaned or the injector's seat resurfaced at the same time, add $150 to $400. Module driver failures are rare but push the job well past this range.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with reductant (def) injector / dosing valve replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.