Powertrain, generic (extended)

P2DD6 Fuel Injection Quantity B Higher Than Expected

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

With P2DD6 the engine control has found that path B injects more fuel than requested, so the mixture ends up richer than planned. Typical reasons are an injector that drips after closing, a worn nozzle passing extra fuel, or rail pressure above target; a sensor that under-reads airflow can fake the same result. On diesels this shows up as soot: more black smoke and shorter intervals between filter regenerations. No manufacturer publishes P2DD6 itself. Ford's 2023 diesels flag the matching global fault as P0172 once the filtered fueling error exceeds +0.15; GM scales its upper limit for A with ambient pressure. P2DD5 is the shortfall in path B, P2DD8 the same excess during cold start.

Likely causes

Injector in group B dripping or nozzle worn
Rail pressure above target (regulator, pressure sensor)
Airflow sensor reading low or intake leak after the sensor
Wrong injector part fitted

Symptoms

  • Check engine light on
  • Black smoke, more frequent particulate filter regeneration
  • Higher fuel consumption

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–3,500
Time0.5–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel injector group bfuel railecm

Related codes

P2DD5P2DD8P026DP2DDDP2DDFP0172

References: law.cornell.edu, gsi.ext.gm.com, fordservicecontent.com.