Powertrain, generic · Fuel and air metering (injector circuit)

P026D Fuel Injection Quantity A Higher Than Expected

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

From 2010, CARB requires diesel engines to detect when the commanded injection quantity is not delivered. The module estimates the fuel actually burned from airflow and the measured lambda (from the NOx or oxygen sensor) and corrects the quantity; if that correction passes a limit, the code sets. P026D means the engine gets more fuel than commanded. GM's LML diesel sets it at idle at a correction of +16 to +35 mm³ per stroke for 12 s, two trips. Volvo trucks detect it as too little oxygen at the NOx sensors for the fuel flow and point to boost sensor, EGR valve and sensor, wrong injectors, turbo vanes and intake leaks. On GM's 2.8 litre diesel vans of 2020–2022 it could also be a software anomaly without driving problems. Symptoms are black smoke and more frequent filter regeneration.

Likely causes

Injector dripping or worn, or wrong injector type fitted
EGR valve not closing or EGR differential pressure sensor wrong
Boost sensor or turbo vanes faulty, intake leak
NOx or oxygen sensor reading wrong
Software

Symptoms

  • Check engine light on
  • Black smoke, higher soot load, more frequent filter regeneration
  • Rough running or idle
  • Often nothing noticeable while driving

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–4,000
Time0.5–6 h

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

Parts involved

fuel injectorsegr valvenox sensor

Related codes

P026CP027FP0263P020AP026BP0087

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.