Diesel Trouble Codes

Black Smoke Under Load — 6.7 Cummins (EGR + DPF, pre-SCR)

Diagnostic reference for black smoke under load on 2007.5–2012 6.7L Cummins EGR+DPF pre-SCR.

Updated October 15, 2026

What’s going on

Black smoke under load on this engine means excess fuel is being burned incompletely. With a working DPF, visible black smoke should not happen; it indicates soot is getting past a cracked or failed filter, usually on top of an engine making too much soot from low boost, an injector problem or EGR faults.1

Most likely causes

  1. VGT turbo underboost / actuator fault — Holset HE351VE VGT with electric actuator and integrated position sensor. Low boost from sooted/sticking vanes, actuator fault, or boost leak causes over-fueling and black smoke under load. Often sets P0299 and/or P2262.23
  2. Injector over-fueling / imbalance — Common-rail solenoid injectors can dribble or over-fuel, producing black smoke under load and excess soot loading. Typical related code P0263.1
  3. EGR system fault increasing soot production — EGR flow issues can contribute to excess soot generation. Related code P0401.14
  4. DPF failure / cracked substrate allowing soot passage — With a working DPF visible black smoke should not happen. A cracked or failed filter lets soot pass, often after excess soot from engine faults. Related code P2002.15

How to narrow it down

  1. Read stored trouble codes first; note P0299, P2262, P0263, P0401, P2002 if present.
  2. Inspect boost pressure vs. commanded under load; check VGT actuator response and position sensor data for HE351VE electric actuator faults.
  3. Check fuel rail pressure and injector balance rates; look for over-fueling or a faulty injector indicated by P0263.
  4. Inspect EGR valve operation and flow; verify EGR-related data for insufficient flow P0401.
  5. Measure DPF differential pressure and review regeneration history; evaluate DPF efficiency for P2002 and signs of cracking or failure allowing soot passage.

Common mistake to avoid

Skipping the VGT actuator calibration. The 6.7 Cummins Holset actuator has to be relearned with a scan tool after it is replaced or disconnected, or boost control will stay off. Source: OBDAdvisor — diesel limp mode diagnosis.

Parts and tools you may need

Tools you’ll need

Rough cost and difficulty

Likely repairPartsShop laborWho usually does it
EGR valve/passage carbon cleaning$20–$1001–4 hrsDIY with tools and a manual
Fuel injector (each)$350–$7001–2 hrsShop
DPF professional cleaning (bake and blow)$300–$7001–3 hrsShop
Electronic VGT actuator (needs calibration)$500–$1,4001–2 hrsDIY with tools and a manual

Typical US independent-shop figures; labor runs about $120–$180 per hour (dealers charge more). Confirm the diagnosis before buying parts.

When to see a pro

If high-pressure fuel system work is needed, or if turbocharger removal/service is required, have a qualified diesel technician perform the work. Do not attempt step-by-step repair of safety-critical systems. If the vehicle enters limp mode or shows sudden power loss, stop driving and seek professional diagnosis.

Check for recalls

Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.

Sources

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

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

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

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

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