Turbocharger Number 1 Speed Low – Data Valid but Below Normal Operational Range – Moderately Severe Level
|Fault Code: 687
Turbocharger Number 1 Speed Low – Data Valid but Below Normal Operational Range – Moderately Severe Level. Low turbocharger speed detected by the ECM.
Engine power derate. The ECM uses an estimated turbocharger speed.
Turbocharger Speed Low
The turbocharger speed sensor is a variable reluctance speed sensor. It consists of a coil of wire and an iron core. A signal is generated as the turbocharger shaft spins. The target on the turbocharger shaft is a ground flat in the center of the shaft.
The turbocharger speed sensor is mounted in the center housing of the turbocharger.
This fault may come active if the electronic control module (ECM) senses boost pressure and engine speed while at the same time a turbocharger speed signal is not present.
Items that can fail and cause this fault code include:
- Turbocharger speed sensor
- Engine harness
- Barometric pressure sensor
- Intake manifold pressure sensor
This fault becomes inactive any time the speed signal from the turbocharger speed sensor returns.
If the fault occurs intermittently, look for causes of intermittent open circuit or short circuits in the turbocharger speed sensor circuit (including the speed sensor pigtail connector).