SPN 2791 - FMI 4 (Fault Code 2351)

SPN2791 FMI4
EGR Valve Control Circuit - Voltage Below Normal or Shorted to Low Source

ISB, ISC, and ISL with CM2150 - EGR Valve Position Circuit

Fault Code: 2351
PID(P), SID(S): S146
SPN: 2791
FMI: 4
Lamp: Amber

REASON: EGR Valve Control Circuit - Voltage Below Normal or Shorted to Low Source. Motor terminal or motor coil short circuit to ground or power supply has been detected by the ECM.

EFFECT: EGR valve actuation will be disabled.

Circuit Description:
The exhaust gas recirculation (EGR) valve is opened by a motor located on top of the EGR valve. A motor shaft extends from the motor and contacts the dual-poppet valve to open the EGR valve. The EGR valve motor does not actually retract the EGR valve. The motor current is reduced and the spring pushes the EGR valve closed.

Component Location:
The EGR valve is located on the air intake connection.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault Codes:
The electronic control module (ECM) detects a short circuit in the EGR motor supply circuits.

Action Taken When the Fault Code is Active:
• The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
• The EGR valve operation will be disabled.

Conditions for Clearing the Fault Code:
The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.

Shop Talk:
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.

Possible causes of this fault code include:
• EGR motor circuit shorted to ground
• EGR motor circuit shorted to battery supply.

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