Powertrain, generic (extended)

P2579 Turbocharger/Supercharger Speed Sensor A Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2579 means speed sensor A delivers a signal, but the shaft speed it reports does not fit the operating state the engine computer expects from boost, airflow and load. PACCAR bulletin E209 for 2017-2019 MX-11 and MX-13 truck engines treats P2579, alone or with P1581, as a fix-as-fail item: the sensor is replaced, because it tends to fail intermittently with a loss of power that disappears when the driver lifts off and presses the pedal again. Ram flash bulletins 18-019-20 to 18-007-24 for 2019 Ram 3500-5500 cab chassis with the 6.7 L Cummins list P2579 among codes cured by new engine software. Bentley sees it on the W12 in either engine control unit. Circuit faults are P2578 and P2580-P2582.

Likely causes

Speed sensor A dropping out intermittently
Engine software that misjudges the speed plausibility (update available on some models)
Intake or boost leak that makes the shaft speed differ from the model
Mechanical turbocharger problem such as bearing drag or wheel damage

Symptoms

  • Sudden loss of power that returns after lifting off the accelerator
  • Malfunction indicator lamp on
  • Turbo speed in live data jumping or inconsistent with boost

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–700
Time0.5–3 h

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

Parts involved

turbo speed sensor aturbocharger

Related codes

P2578P2580P2581P2582P2594P0299

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.