Diesel Trouble Codes

P0090 — Fuel Pressure Regulator Control Circuit (6.7 Cummins (EGR + DPF, pre-SCR))

P0090 means the ECM has detected an electrical fault in the circuit that controls the fuel pressure regulator on a 6.7L Cummins 2007.5–2012 EGR+DPF pre-SCR.

Updated September 2, 2026

What it means

On this platform the fuel pressure regulator is the Fuel Control Actuator (FCA/MPROP) on the Bosch CP3 high-pressure pump. The ECM monitors the FCA control circuit; P0090 is set for an electrical fault in that control circuit, not a mechanical rail-pressure issue.1

Most likely causes

  1. FCA/MPROP electrical connector or wiring open/short to ground or power — Inspect the FCA connector at the CP3 pump for corrosion, backed-out pins, chafing, or oil intrusion; check harness continuity and isolation to ground/power. The ECM detects an electrical fault in the fuel pressure regulator control circuit.1
  2. ECM driver fault for the FCA control circuit — If wiring and FCA coil resistance are normal, the ECM internal driver may be faulty. The generic definition is an electrical fault in the circuit that controls the fuel pressure regulator.1
  3. FCA/MPROP coil internal open/short — Measure FCA coil resistance per service spec; an out-of-range reading indicates a failed actuator. The code is for the fuel pressure regulator control circuit on the CP3 system.1

How to diagnose

  1. Verify code P0090 is present and check freeze-frame for engine state.
  2. Visually inspect CP3 pump FCA connector and harness for damage, oil, corrosion; repair as needed.
  3. Measure FCA coil resistance at the actuator connector and compare to spec; replace FCA if out of spec.
  4. Check FCA control circuit wiring for continuity, shorts to ground/power between ECM and FCA; repair wiring if fault found.
  5. If wiring and FCA are good, perform ECM pin-out tests per service info to confirm ECM driver integrity.
  6. Clear codes and retest; monitor rail pressure control with scan tool to confirm normal regulation.

Parts and tools you may need

Rough cost and difficulty

Parts cost varies by supplier and labor rates; diagnostic time is typically 0.5–1.5 h plus any FCA or wiring repair.

When to see a pro

If wiring tests pass and FCA tests good but P0090 returns, have the ECM evaluated by a qualified diesel technician. Do not attempt high-pressure fuel system disassembly. If the engine stalls or loses power while driving, stop and tow; sudden loss of power can affect steering/braking assist.

Sources

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