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

P02E8 Diesel Intake Air Flow A Position Sensor Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

The diesel intake air flow valve A is the throttle flap ahead of the intake manifold of a diesel engine: it creates the vacuum needed for high EGR rates, lowers airflow to heat the particulate filter and catalyst during regeneration and closes at switch-off against run-on shaking. A spring holds it open when unpowered; an electric motor positions it, with a position sensor reporting back. P02E8 means the position signal is below its range – a signal wire shorted to ground or an open 5 V supply or signal wire. GM's LML sets it below 0.40 V for 5 s in the first trip, newer GM diesels with digital sensors below 1–5 % of 5 V after two trips; Ford's diesels below 0.08 V for 3 s. On a fault the valve is switched off and the spring opens it: driving is usually little affected, but EGR control is restricted and filter regeneration may be blocked.

Likely causes

Signal wire shorted to ground or 5 V supply open
Sensor faulty
Connector corroded
5 V reference loaded by another sensor

Symptoms

  • Check engine light on
  • Often no noticeable change
  • Filter regeneration does not run, soot load rises

Repair estimate

DifficultyMediumDIY possible
Parts and labour€50–500
Time0.5–2 h

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

Parts involved

diesel intake throttle position sensordiesel intake throttle valvesensor wiring

Related codes

P02E9P02E7P02E6P02EAP0122

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