P2DD7Cold Start Fuel Injection Quantity B Lower Than Expected
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2DD7 limits the shortfall of P2DD5 to the cold-start phase. Many engines inject differently just after a cold start, with extra or shifted injections that heat the catalyst or SCR system. CARB section 1968.2 (f)(12.1.2) requires diesels to keep faults found while this strategy runs apart from the same faults in normal operation, and (f)(12.2.3) adds a check that the commanded injection quantity actually responds, phased in over 2026 to 2028. GM's 2025 diesels show the pattern with separate cold-start codes for rail pressure (P2C1F) and injection timing (P05EC), but not for quantity. No maker documents P2DD7. Fuel thickened by cold, a clogged filter or slow pressure build-up fit here; the engine may run roughly until warm.
- What you may notice
- Check engine light on after a cold start
- Hard cold start, rough running while cold
- Longer warm-up
- Likely causes
- PossibleFuel filter restricted, fuel waxing in cold weather
- PossibleRail pressure builds too slowly after start
- PossibleInjectors of group B sluggish or partly blocked
- RareCoolant or fuel temperature signal implausible
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.