LB7 Duramax Diagnostics

GM Silverado/Sierra 2500HD/3500, 2001-2004 — the first Duramax: CP3 common rail, LB7 injectors (a known weak point), fixed-geometry turbo, glow plugs, and no emissions system. Injector, fuel-pressure and glow-plug codes.

Common symptoms

Engine Stalls or Dies While Driving — LB7 Duramax A concise diagnostic reference for LB7 Duramax (2001–2004) stalling or dying while driving, focused on fuel rail pressure loss and crank/cam signal loss.
Fuel in the Oil or Rising Oil Level — LB7 Duramax A diagnostic reference for LB7 Duramax (2001–2004) when the engine oil level rises, the oil smells of diesel, or owners report fuel contamination of the…
Hard Start or Long Crank — LB7 Duramax A concise diagnostic reference for hard start or long crank on the 2001–2004 GM 6.6L LB7 Duramax.
Loss of Power Under Load — LB7 Duramax Diagnostic reference for LB7 Duramax (2001–2004) loss of power under load, including related trouble codes P1093, P0087, P0299, P0234, P0237, P0238.
Reduced Power or Poor Throttle Response — LB7 Duramax Diagnostic reference for LB7 Duramax (2001–2004) reduced power or poor throttle response. Covers accelerator pedal position system faults and related…
Rough Idle, Misfire or Smoke — LB7 Duramax Diagnostic reference for rough idle, misfire and smoke on 2001–2004 GM Silverado/Sierra 2500HD/3500 6.6L LB7 Duramax. Covers injector-related causes and how to…

P0101 — Mass or Volume Air Flow Sensor A Circuit Range/Performance — LB7 Duramax Diagnostic reference for LB7 Duramax (2001–2004) P0101.
P0191 — Fuel Rail Pressure Sensor A Circuit Range/Performance — LB7 Duramax Fuel Rail Pressure Sensor A Circuit Range/Performance
P0205 — Injector Circuit/Open - Cylinder 5 — LB7 Duramax Diagnostic guide for P0205 on LB7 Duramax (2001–2004).
P0206 — Injector Circuit/Open - Cylinder 6 — LB7 Duramax The ECM has detected an electrical fault in the cylinder 6 injector circuit on the LB7 Duramax. The LB7 injectors sit under the valve covers and are a known…
P0207 — Injector Circuit/Open - Cylinder 7 — LB7 Duramax The ECM has detected an electrical fault in the cylinder 7 injector circuit. On the LB7 the injectors sit under the valve covers and are a well-known weak…
P0208 — Injector Circuit/Open - Cylinder 8 — LB7 Duramax Diagnostic reference for LB7 Duramax (2001–2004) P0208.
P0238 — Turbocharger/Supercharger Boost Sensor A Circuit High — LB7 Duramax Diagnostic reference for LB7 Duramax (2001–2004) P0238.
P1125 — Accelerator Pedal Position (APP) System — LB7 Duramax Diagnostic reference for P1125 on LB7 Duramax (2001–2004).
P1093 — Fuel Rail Pressure Low During Power Enrichment — LB7 Duramax Diagnostic reference for LB7 Duramax (2001–2004) P1093.
P0090 — Fuel Pressure Regulator Control Circuit — LB7 Duramax Diagnostic reference for LB7 Duramax (2001–2004) P0090.
P0087 — Fuel Rail/System Pressure Too Low — LB7 Duramax Measured fuel rail pressure is below the PCM's commanded value. On the LB7 Duramax this is a CP3 common-rail pressure control issue.
P0088 — Fuel Rail/System Pressure Too High — LB7 Duramax Measured fuel rail pressure exceeds the commanded value on the LB7 Duramax CP3 common-rail system.
P0089 — Fuel Pressure Regulator Performance — LB7 Duramax The engine control module has detected that the fuel pressure regulator is not maintaining fuel pressure within the expected range.
P0128 — Coolant Thermostat Below Regulating Temperature — LB7 Duramax Engine coolant does not reach the expected operating temperature in the expected time.
P0182 — Fuel Temperature Sensor A Circuit Low — LB7 Duramax Diagnostic reference for LB7 Duramax 2001-2004. P0182 is not applicable to this platform because the LB7 has no fuel temperature sensor and the ECM does not…
P0192 — Fuel Rail Pressure Sensor Circuit Low Input — LB7 Duramax The ECM sees the fuel rail pressure sensor signal voltage lower than expected on the LB7 Duramax.
P0193 — Fuel Rail Pressure Sensor A Circuit High — LB7 Duramax Diagnostic reference for LB7 Duramax (2001-2004) P0193.
P0201 — Injector Circuit/Open - Cylinder 1 — LB7 Duramax P0201 indicates the ECM has detected an electrical fault in the fuel injector circuit for cylinder 1 on the LB7 Duramax.
P0202 — Injector Circuit/Open - Cylinder 2 — LB7 Duramax P0202 on the LB7 Duramax means the ECM has detected an electrical fault in the fuel injector circuit for cylinder 2. The LB7 uses Bosch injectors mounted under…
P0203 — Injector Circuit/Open - Cylinder 3 — LB7 Duramax P0203 on the LB7 Duramax means the ECM has detected an electrical fault in the injector circuit for cylinder 3. The LB7 uses Bosch injectors mounted under the…
P0204 — Injector Circuit/Open - Cylinder 4 — LB7 Duramax P0204 indicates the ECM has detected an electrical fault in the fuel injector circuit for cylinder 4 on the LB7 Duramax.
P0234 — Turbocharger/Supercharger Overboost Condition — LB7 Duramax P0234 is set when the ECM detects boost pressure above the calibrated maximum for current operating conditions on the LB7 Duramax. The LB7 uses an IHI…
P0237 — Turbocharger/Supercharger Boost Sensor A Circuit Low — LB7 Duramax Diagnostic reference for P0237 on LB7 Duramax (2001–2004).
P0299 — Turbocharger/Supercharger Underboost Condition — LB7 Duramax Diagnostic reference for LB7 Duramax (2001-2004) P0299.
P0300 — Random/Multiple Cylinder Misfire Detected — LB7 Duramax Diagnostic reference for P0300 on LB7 Duramax (2001–2004).
P0335 — Crankshaft Position Sensor A Circuit Malfunction — LB7 Duramax Diagnostic reference for LB7 Duramax (2001–2004) P0335.
P0341 — Camshaft Position Sensor A Circuit Range/Performance — LB7 Duramax Diagnostic reference for LB7 Duramax (2001-2004) P0341.
P0380 — Glow Plug/Heater Circuit Malfunction — LB7 Duramax P0380 on the LB7 Duramax means the ECM has detected an electrical fault in the glow plug heater circuit. The LB7 uses eight glow plugs controlled by a glow…
P0670 — Glow Plug Control Module Circuit — LB7 Duramax The PCM has detected a fault in the glow-plug control module circuit on the LB7 Duramax. This is a cold-start system fault; the Duramax uses glow plugs with a…