Powertrain, generic (extended)

P2397 Diesel Intake Air Flow B Position Sensor Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2397 covers a B-throttle position signal that stays inside its electrical window but does not make sense, for instance a reading that does not move when the motor is driven, or one that disagrees with the commanded angle. CARB asks for such rationality checks on inputs wherever feasible. No published manufacturer table covers P2397. The 6.6 L LML calibration from GM handles the A valve this way under P02E7 and flags a control deviation beyond ±10 % lasting 10 s. Because a sticking flap and a drifting sensor produce the same pattern, compare the scan-tool angle with the real flap position and check the sensor's contact resistance before blaming the actuator. The MIL and reduced EGR control are the main effects; some engines also cut power.

Likely causes

Sticking flap that lags behind the command
Worn potentiometer track or drifting sensor
Contact resistance in connector or signal wire
Play between gear and flap shaft

Symptoms

  • MIL on
  • Displayed flap angle does not follow the command
  • Occasionally reduced power

Repair estimate

DifficultyMediumDIY possible
Parts and labour€50–600
Time0.5–2.5 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

P2391P2396P2398P2399P02E7

References: law.cornell.edu, gsi.ext.gm.com, ms-motorservice.com.