Duramax Fault Codes
The 6.6L Duramax V8 is a joint GM / Isuzu diesel that has powered Chevrolet Silverado HD and GMC Sierra HD trucks since 2001. Six major generations -- LB7, LLY, LBZ, LMM, LML, and L5P -- cover mechanical improvements, emissions regulation compliance (DPF, SCR), and horsepower increases from 235 HP up to today's 445 HP / 910 lb-ft L5P.
248 fault codes documented· 6 generations · P-codes + SPN/FMI · 2001 - present
Most Common Duramax Fault Codes
Showing 24 of 248 Duramax codes, sorted by severity. Each links to causes, diagnostics, common fixes, and repair cost estimates.
DURAMAX-B0081 critical
Deployment Commanded
DURAMAX-B1001 critical
ECU Defective
DURAMAX-P0087 critical
Fuel Rail / System Pressure Too Low
DURAMAX-P0088 critical
Fuel Rail / System Pressure Too High
DURAMAX-P0217 critical
Engine Coolant Over Temperature Condition
DURAMAX-P0524 critical
Engine Oil Pressure Too Low
DURAMAX-P0601 critical
Internal Control Module Memory Check Sum Error
DURAMAX-P0602 critical
Control Module Programming Error
DURAMAX-P0604 critical
Internal Control Module Random Access Memory Error
DURAMAX-P0605 critical
Internal Control Module Read Only Memory Error
DURAMAX-P0606 critical
ECM/PCM Processor Fault
DURAMAX-P0607 critical
Control Module Performance
DURAMAX-P207F critical
Reductant Quality Performance
DURAMAX-P20EE critical
SCR NOx Catalyst Efficiency Below Threshold Bank 1
DURAMAX-P2428 critical
Exhaust Gas Temperature Too High Bank 1
DURAMAX-P2463 critical
Diesel Particulate Filter Restriction — Soot Accumulation
DURAMAX-P2463_SOOT critical
Diesel Particulate Filter Soot Accumulation — Service Required
DURAMAX-P24A4 critical
Diesel Particulate Filter Restriction — Forced Regeneration Limit Reached
DURAMAX-P2BAC critical
NOx Exceedance — Deactivation of EGR
DURAMAX-C0035 serious
Left Front Wheel Speed Sensor Circuit
DURAMAX-C0040 serious
Right Front Wheel Speed Sensor Circuit
DURAMAX-C0045 serious
Left Rear Wheel Speed Sensor Circuit
DURAMAX-C0050 serious
Right Rear Wheel Speed Sensor Circuit
DURAMAX-P003A serious
Turbocharger Boost Control 'A' Position Exceeded Learning Limit
Duramax Generations
| Engine | Years | Applications | Notes |
|---|---|---|---|
| LB7 | 2001-2004 | Chevy/GMC 2500HD & 3500HD | Original Duramax. No DPF, mechanical injectors later recalled for fuel contamination issues. |
| LLY | 2004.5-2005 | Chevy/GMC 2500HD & 3500HD | Added EGR. Known for head gasket issues and overheating when towing. |
| LBZ | 2006-2007 | Chevy/GMC 2500HD & 3500HD | Considered the most reliable pre-DPF Duramax. No DPF, no regen cycles. |
| LMM | 2007.5-2010 | Chevy/GMC 2500HD & 3500HD | First Duramax with DPF. DPF regen faults and EGR issues common. |
| LML | 2011-2016 | Chevy/GMC 2500HD & 3500HD | Added SCR/DEF. CP4.2 high-pressure pump failures are infamous and expensive. |
| L5P | 2017-present | Chevy Silverado HD, GMC Sierra HD | 445 HP / 910 lb-ft. Returned to a CP4-based HPFP but with revised tolerances. Locked ECU (tuning restricted). |
Common Duramax Issues
- CP4.2 high-pressure fuel pump catastrophic failure (LML 2011-2016) -- sends metal debris through the entire fuel system
- DEF system faults on LML and L5P: doser valve, DEF quality sensor, heater issues
- Turbo vane position sensor and sticking VGT on LMM, LML
- EGR cooler cracking and coolant loss, especially on LLY and LMM
- Allison transmission TCM codes (P0700, P0842, P0776) often paired with Duramax engine codes