P2047 — Reductant Injector Circuit/Open Bank 1 Unit 1 — L5P Duramax

Diagnostic reference for L5P Duramax (2017–present) P2047.

Updated October 15, 2026

What it means

The ECM has detected an open or fault in the DEF (reductant) injector circuit. On the L5P this is the DEF dosing injector circuit for Bank 1 Unit 1. GM DEF warnings can lead to a speed limit if the fault is not repaired.¹

Most likely causes

1. DEF injector electrical connector damaged, corroded, or loose at the exhaust-mounted injector — Heat and vibration near the exhaust can degrade the injector connector and terminals, producing an open or intermittent circuit.¹
2. Wiring harness chafed, melted, or broken between ECM and DEF injector — Routing near hot exhaust components can cause insulation damage and opens in the injector control wires.¹
3. DEF injector internal coil open or failed — An open winding inside the reductant injector will set a circuit/open fault.¹
4. ECM driver or related control circuit fault — A fault in the ECM output driver or internal circuitry can be interpreted as an open in the injector circuit.¹

How to diagnose

1. Verify code P2047 is present and check for accompanying DEF/SCR codes such as P204F, P203F, P20E8, P20EE, P2BAD, P2201.
2. Inspect DEF injector connector at the exhaust for heat damage, corrosion, or loose terminals; check connector seating and terminal tension.
3. Inspect wiring harness from ECM to DEF injector for chafing, melting, or breaks, especially near hot exhaust and sharp edges.
4. Perform a visual and continuity check of the injector control circuit with a scan tool and multimeter to confirm an open or high resistance condition.
5. Check ECM connector and related terminals for corrosion or damage; confirm ECM power/ground integrity before condemning the ECM.

Specs and test values

Common mistake to avoid

Replacing sensors, the doser or the SCR catalyst before testing the DEF. Old, heat-stored or diluted DEF loses strength and sets the same efficiency codes. Check it with a refractometer first. Source: Ram service bulletin 25-005-14 (Diesel Exhaust Fluid).

Parts and tools you may need

• Digital multimeter
• Scan tool with GM enhanced diagnostics
• Terminal release tools
• Inspection mirror and light

Tools you’ll need

• OBD-II scan tool — Read and clear P2047 and related DEF/SCR codes to confirm the fault and monitor live reductant injector data.
• digital multimeter — Measure continuity and resistance of the DEF injector control circuit to identify opens or high resistance in wiring and coil.
• inspection mirror — View the exhaust-mounted DEF injector connector and harness routing in tight, hot areas without disassembly.
• terminal release tool set — Safely disconnect and inspect DEF injector and ECM terminals for corrosion, damage, or poor tension.

Rough cost and difficulty

Typical US independent-shop figures; labor runs about $120–$180 per hour (dealers charge more). Confirm the diagnosis before buying parts.

When to see a pro

If wiring damage is extensive, the injector tests inconclusive, or ECM involvement is suspected, have a qualified diesel technician diagnose and repair the DEF dosing circuit.

Check for recalls

Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.

Sources

Repair videos: P2047 on the L5P Duramax

Third-party videos, not ours — picked for this engine. Confirm anything against the factory service information for your truck.

2018 Silverado 2500 DEF injector replacement — C Farmer · 44K views

Duramax DEF Injector Replacement | Installation Spotlight — Standard Brand · 68K views