Circuit DescriptionThe turbocharger speed sensor is a variable reluctance speed sensor. It consists of a coil of wire and an iron core. The target on the turbocharger shaft is a ground flat in the center of the shaft. As the flat on the turbocharger shaft spins past the speed sensor, a signal is generated. The ECM interprets this signal and converts it to a turbocharger speed reading.

Component LocationThe turbocharger speed sensor is mounted in the center housing of the turbocharger.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the engine is operating.

Conditions for Setting the Fault CodesThe ECM detects that the turbocharger speed is less than 600 rpm for more than 1 second when the engine speed is greater than 1200 rpm.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.The ECM will estimate turbocharger speed.Conditions for Clearing the Fault CodeTo validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop-and-go city driving and steady state highway driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.To validate the repair using a Chassis Dynamometer Test, utilize a routine that incorporates acceleration and motoring events, steady state highway operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.For On-Board Diagnostic (OBD) engines, the ECM will turn off the MIL after three consecutive trips where the diagnostic runs and passes.The ?Reset All Faults? command in INSITE? electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications

Shop TalkItems that can cause this fault code include:

Damaged turbocharger speed sensorDamaged engine harnessDamaged ECM.If the fault occurs intermittently, look for causes of intermittent open or short circuits in the turbocharger speed sensor circuit (including the speed sensor pigtail connector). For the fault code to clear, the ratio of boost pressure to ambient pressure must be above 1.19:1 for at least 30 consecutive seconds. This condition can only be achieved during a test drive when the engine is under load.

Operating the engine at idle or high idle while stationary will not create enough load to maintain boost pressure at 1.19 times ambient pressure for 30 consecutive seconds. .

Although it is possible for a damaged ECM to be the root cause of this fault code, it is highly unlikely. ECM replacement should only be considered as a last resort, if no other repairs are successful in clearing the fault code.

In very rare cases, it has been shown that the turbocharger can cause this fault code to come active and turbocharger replacement may be the only way to clear the fault code.

Possible Cause:1) Turbocharger speed sensor failure2) Engine Harness/ Connector failure3) ECM calibration