PACCAR PX-6 CM2150 (2007-09) Fault Code: 1943 PID: SPN: 3555 FMI: 1 Ambient Air Density – Data Valid but Below Normal Operational Range – Least Severe Level. Engine torque has been reduced because the vehicle was operating at a high altitude condition.

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.

When the engine has been operated in a high altitude location, this fault code is logged. This fault code is for information only and no repairs are necessary. The engine can possibly be derated when operating in the high altitude location to protect the turbocharger and engine from excessively high exhaust temperatures. The derate limits the torque output of the engine to keep the temperatures below the maximum temperature limits.

Note: This fault code will most likely not be active with no load in the shop. The engine must be under the same operating condition (altitude and temperature) at the time that it had originally logged.

Possible repairs:

1)Replace the barometric pressure sensor.