PACCAR PX-8 CM2150 (2007-09) Fault Code: 249 PID: 171 SPN: 171 FMI: 3 Ambient Air Temperature Sensor 1 Circuit – Voltage Above Normal or Shorted to High Source. High signal voltage detected at ambient air temperature circuit.
Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM.
The ambient air temperature sensor shares return wires in the engine harness with other sensors. Opens and shorts in the engine harness can cause multiple fault codes to be active. Check active fault codes with multiple counts first.
Possible causes:
1)Open return circuit in the harness, connectors, or sensor
2)Open signal circuit or shorted to voltage source.
Possible repairs:
1)Replace the ambient air temperature sensor.
2)Replace the ECM.
3)Repair or replace the engine harness.
PACCAR PX-8 CM2150 (2007-09) Fault Code: 245 PID: SID 033 SPN: 647 FMI: 4 Fan Control Circuit – Voltage Below Normal or Shorted to Low Source. Low signal voltage detected at the fan control circuit when commanded ON.
PACCAR PX-8 CM2150 (2007-09) Fault Code: 242 PID: 84 SPN: 84 FMI: 10 Wheel-Based Vehicle Speed Sensor Circuit Tampering Has Been Detected – Abnormal Rate of Change. Signal indicates an intermittent connection or VSS tampering.
PACCAR PX-8 CM2150 (2007-09) Fault Code: 241 PID: 84 SPN: 84 FMI: 2 Wheel-Based Vehicle Speed – Data Erratic, Intermittent, or Incorrect. The ECM lost the vehicle speed signal.
PACCAR PX-8 CM2150 (2007-09) Fault Code: 239 PID: SID 232 SPN: 3511 FMI: 3 Sensor Supply 3 Circuit – Voltage Above Normal or Shorted to High Source. High voltage detected at sensor supply number 3 circuit.
PACCAR PX-8 CM2150 (2007-09) Fault Code: 238 PID: SID 232 SPN: 3511 FMI: 4 Sensor Supply 3 Circuit – Voltage Below Normal or Shorted to Low Source. Low voltage detected on the +5 volt sensor supply circuit to the engine speed sensor.
PACCAR PX-8 CM2150 (2007-09) Fault Code: 234 PID: 190 SPN: 190 FMI: 0 Engine Crankshaft Speed/Position – Data Valid but Above Normal Operational Range – Most Severe Level. Engine speed signal indicates engine speed above engine protection limit.
