L5P Duramax Diagnostics
GM Silverado/Sierra 2500HD/3500HD, 2017-present — the current Duramax: CP4.2 common rail, variable-geometry turbo, and the full EGR/DPF/SCR emissions set. Fuel-pressure, VGT, EGR, DPF and DEF codes.
- P003A — Turbocharger Boost Control Position Sensor/Switch Circuit Range/Performance (L5P Duramax) Diagnostic reference for L5P Duramax (2017–present) P003A. Platform facts are authoritative and override any conflicting source.
- P0087 — Fuel Rail/System Pressure Too Low (L5P Duramax) Measured fuel rail pressure is below the PCM's commanded value on the L5P Duramax (2017–present 6.6L). The L5P uses a Bosch CP4.2 high-pressure pump with an…
- P0088 — Fuel Rail/System Pressure Too High (L5P Duramax) Measured fuel rail pressure exceeds the commanded value on the L5P Duramax (2017–present 6.6L). The CP4.2 high-pressure pump regulates rail pressure via its…
- P0090 — Fuel Pressure Regulator Control Circuit (L5P Duramax) Diagnostic reference for P0090 on L5P Duramax (2017–present).
- P00FF — Fuel Pressure Regulator Control Circuit/Open (L5P Duramax) Fuel Pressure Regulator Control Circuit/Open
- P0101 — Mass or Volume Air Flow Circuit Range/Performance (L5P Duramax) Mass or Volume Air Flow Circuit Range/Performance
- P0128 — Coolant Thermostat Below Regulating Temperature (L5P Duramax) P0128 is a generic thermostat rationality / low coolant temperature code. On the L5P Duramax (2017–present 6.6L) it typically presents as a mechanical…
- P0201 — Injector Circuit/Open - Cylinder 1 (L5P Duramax) Diagnostic reference for P0201 on L5P Duramax (2017–present).
- P0234 — Turbocharger/Supercharger Overboost Condition (L5P Duramax) P0234 on the L5P Duramax means the ECM has detected boost pressure exceeding the maximum allowed for current conditions. The L5P uses a variable-geometry turbo…
- P0263 — Cylinder 1 Contribution/Balance Fault (L5P Duramax) P0263 on L5P Duramax means the PCM has detected cylinder 1 output deviating from the others. On this platform the fault is an injector or compression issue for…
- P0299 — Turbocharger/Supercharger Underboost Condition (L5P Duramax) Boost pressure is below the minimum expected for current conditions. On L5P Duramax the turbo is a variable-geometry turbo (VGT) with an electric actuator and…
- P0380 — Glow Plug/Heater Circuit Malfunction (L5P Duramax) Diagnostic reference for P0380 on L5P Duramax (2017–present).
- P0401 — Exhaust Gas Recirculation Flow Insufficient (L5P Duramax) Diagnostic reference for L5P Duramax (2017–present) P0401.
- P0420 — Catalyst System Efficiency Below Threshold (L5P Duramax) Diagnostic reference for L5P Duramax (2017–present) when generic OBD-II code P0420 is stored. On this diesel platform the code is not a true catalyst monitor…
- P042E — Exhaust Gas Recirculation Control Stuck Open (L5P Duramax) Diagnostic reference for P042E on L5P Duramax (2017–present).
- P0670 — Glow Plug Control Module Circuit (L5P Duramax) Diagnostic reference for P0670 on L5P Duramax (2017–present).
- P128C — Cylinder 1 Glow Plug Control Circuit High (L5P Duramax) Cylinder 1 Glow Plug Control Circuit High
- P2002 — Diesel Particulate Filter Efficiency Below Threshold (Bank 1) (L5P Duramax) Diagnostic reference for L5P Duramax 2017–present.
- P203F — Exhaust Gas Temperature Sensor Circuit Range/Performance Bank 1 Sensor 2 (L5P Duramax) Exhaust Gas Temperature Sensor Circuit Range/Performance Bank 1 Sensor 2
- P204F — Reductant System Performance (L5P Duramax) Diagnostic reference for P204F on L5P Duramax (2017–present).
- P20E8 — Reductant Pressure Too Low (L5P Duramax) Reductant Pressure Too Low
- P20EE — SCR NOx Catalyst Efficiency Below Threshold (Bank 1) (L5P Duramax) Diagnostic reference for L5P Duramax 2017–present 6.6L. P20EE indicates the SCR NOx conversion efficiency monitor is below threshold. Diagnose by confirming…
- P2452 — Diesel Particulate Filter Pressure Sensor A Circuit (L5P Duramax) Diesel Particulate Filter Pressure Sensor A Circuit
- P2459 — Diesel Particulate Filter Regeneration Frequency (L5P Duramax) Diagnostic reference for P2459 on L5P Duramax (2017–present).
- P2563 — Turbocharger Boost Control Position Sensor Circuit High (L5P Duramax) P2563 on L5P Duramax indicates the ECM sees the VGT position sensor voltage higher than expected. The L5P uses a variable-geometry turbo with an electric…
- P2BAD — NOx Exceedance — Root Cause Unknown (L5P Duramax) NOx Exceedance — Root Cause Unknown