P2579 code meaning
Turbocharger/Supercharger Speed Sensor A Circuit Range/Performance
Powertrain system Generic code P25xx codes Check engine light
What P2579 means
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.
P2579 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P2579
- 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
Common causes of P2579
- Most likelySpeed sensor A dropping out intermittently
- PossibleEngine software that misjudges the speed plausibility (update available on some models)
- PossibleIntake or boost leak that makes the shaft speed differ from the model
- Less likelyMechanical turbocharger problem such as bearing drag or wheel damage
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Turbo speed sensor aTurbocharger
What each part of P2579 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| 79 | The exact fault in that area. |
What to do next
- Note P2579 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2579
What does P2579 mean?
P2579 means "Turbocharger/Supercharger Speed Sensor A Circuit Range/Performance". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P2579?
Drive gently and only to a workshop. With P2579 the car can go into limp mode (reduced power) to protect itself.
Will P2579 fail an emissions test?
Yes, it can. P2579 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2579 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P2579 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.