Electronic Control System Signature, ISX and QSX15 Engines – FAULT CODE 486

Fuel System Underfueling


Fault Code: 486
PID: P129
SPN: 1349
FMI: 1/18
LAMP: Yellow

Unexpectedly low rail pressure was detected on the rear three cylinders.

Low power or rough idle.

Hydraulic Fuel System

Circuit Description

The electronic control module (ECM) supplies voltage to open the fueling actuators for a short length of time. This allows a short pulse of fuel to flow to the injector. The injector then injects this fuel into the cylinder for combustion.

Component Location

The rear fueling actuators are located on the fuel delivery housing below the air inlet horn. It is the actuator that is closest to the rear of the engine. The injectors are located in the cylinder head under the valve cover.

Shop Talk

The ECM measures the amount of fuel metered into the injector by using the rear rail pressure sensor. If the amount of fuel is below what the ECM expected, the fault code is activated.

Refer to Troubleshooting Fault Code t05-486.

Last Modified:  26-Oct-2010