Diesel Trouble Codes

P0202 — Injector Circuit Malfunction Cylinder 2 (6.7 Cummins (EGR + DPF, pre-SCR))

The engine control module has detected an electrical fault in the fuel injector circuit for cylinder number two.

Updated September 2, 2026

What it means

The ECM has detected an electrical fault in the fuel injector circuit for cylinder number two. This is an electrical circuit fault, not a mechanical contribution issue. Typical on this platform: 6.7L Cummins 2007.5-2012 EGR+DPF pre-SCR, CP3 common rail, in-tank lift pump, VGT HE351VE with electric actuator, NAC+DPF, grid heater, mechanical thermostat, gear-driven timing, MAP primary load.1

Most likely causes

  1. Injector 2 solenoid driver or wiring open/short to ground/power — ECM-detected electrical fault in the injector circuit for cylinder 2. Generic definition: ECM detected electrical fault in fuel injector circuit for cylinder number two.1
  2. Chafed/damaged injector harness at valve cover or engine harness — Physical damage to the injector wiring can create an open or short that the ECM flags as a circuit malfunction.1
  3. Corrosion/high resistance at injector 2 connector or ECM connector — Poor terminal contact produces circuit fault detection by the ECM.1
  4. Internal injector solenoid failure — Solenoid coil open/short inside injector 2 triggers circuit malfunction code.1
  5. ECM injector driver fault for cylinder 2 — ECM internal driver failure can set a circuit code for a specific cylinder.1

How to diagnose

  1. Verify code P0202 is present and check freeze frame for conditions.
  2. Inspect injector 2 connector and wiring for damage, corrosion, oil intrusion; check harness routing and chafe points at valve cover.
  3. Perform pin drag test and continuity check of injector 2 circuit from ECM connector to injector connector; compare resistance to other cylinders.
  4. Measure injector 2 solenoid resistance to spec and compare to cylinders 1,3-6; look for open/short.
  5. Swap injector 2 electrical connector with adjacent cylinder harness if possible to see if code follows wiring.
  6. Check ECM connector terminals for corrosion/moisture; inspect ECM grounds and power feeds.
  7. Clear codes and monitor for reset with engine running and during a drive cycle.

Parts and tools you may need

Rough cost and difficulty

Electrical diagnosis is labor-intensive; parts range from wiring repair to injector replacement or ECM service. Actual cost varies by findings.

When to see a pro

If circuit tests normal but code returns, or if ECM driver is suspected, have a qualified diesel technician perform ECM output tests and injector circuit scope verification. Do not attempt high-pressure fuel system disassembly for an electrical code.

Sources

  1. Curated DTC seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎