Pinpoint Test He: Exhaust Gas RECIRCULATION (EGR) Systems: Introduction
Normal Operation
Refer to
DTC Fault Trigger Conditions
| DTC | Description | Fault Trigger Condition |
| PCM P0401:00 |
EGR 'A' Flow Insufficient Detected: No Sub Type Information | Sets when PCM detects the signal from the differential pressure feedback EGR sensor indicates that EGR flow is less than the desired minimum. The EGR system is monitored during steady state driving conditions while the EGR is commanded on. |
| PCM P0402:00 |
EGR 'A' Flow Excessive Detected : No Sub Type Information | Sets when PCM
detects the signal at idle is greater than at KOEO
by a calibrated amount. The EGR
system is monitored for undesired EGR
flow during idle. The EGR
monitor looks at the differential pressure feedback EGR
signal at idle and compares it to the stored signal measured during KOEO. A DPFEGR PID reading that is greater at idle than during KOEO by 0.5 volt or a rough engine idle may indicate a concern. On some applications P0402 can set while driving. View the freeze frame data to determine the operating conditions when the DTC was set. |
| PCM P044C:00 |
EGR Sensor 'C' Circuit Low : No Sub Type Information |
Sets when PCM detects the average voltage to the PCM drops to a voltage less than the minimum calibrated value. The EGR monitor checks the differential pressure feedback EGR sensor signal to the PCM for low voltage. |
| PCM P044D:00 |
EGR Sensor 'C' Circuit High : No Sub Type Information |
Sets when PCM detects the average voltage to the PCM exceeds the maximum calibrated value. The EGR monitor checks the differential pressure feedback EGR sensor signal to the PCM for high voltage. |
| PCM P139A:00 |
EGR Sensor 'C' Hoses Reversed: No Sub Type Information | Sets when PCM
detects the average the differential pressure indicated by the sensor exceeds a maximum threshold or falls below a minimum threshold. At idle, the EGR
monitor commands the EGR valve closed and checks the differential pressure across the EGR tube orifice which should be zero to indicate the hoses are connected and not restricted. Look for signs of water or icing in the hose. Verify the hose connection and routing. Check the differential pressure feedback EGR sensor for correct mounting and function. |
| PCM P139B:00 |
EGR Sensor 'C' Upstream Hose Off or Plugged: No Sub Type Information |
Sets when PCM
detects the differential pressure indicated by the sensor exceeds a maximum threshold or falls below a minimum threshold. At idle, the EGR
monitor commands the EGR valve closed and checks the differential pressure across the EGR tube orifice which should be zero to indicate the hoses are connected and not restricted. Look for signs of water or icing in the hose. Verify the hose connection and routing. Check the differential pressure feedback EGR sensor for correct mounting and function. |
| PCM P139C:00 |
EGR Sensor 'C' Downstream Hose Off or Plugged: No Sub Type Information |
Sets when PCM
detects the differential pressure indicated by the sensor exceeds a maximum threshold or falls below a minimum threshold. At idle, the EGR
monitor commands the EGR valve closed and checks the differential pressure across the EGR tube orifice which should be zero to indicate the hoses are connected and not restricted. Look for signs of water or icing in the hose. Verify the hose connection and routing. Check the differential pressure feedback EGR sensor for correct mounting and function. |
| PCM P1408:00 |
EGR Flow Out Of Self Test Range: No Sub Type Information |
Sets when PCM detects the measured EGR flows falls above or below the required calibration. This test is carried out during the key ON, KOER on demand self-test only. The EGR system is commanded on at a fixed engine speed. |
| PCM P2457:00 |
EGR Cooler 'A' Efficiency Below Threshold: No Sub Type Information |
Sets when PCM detects the difference between the expected temperature of the exhaust gas and the actual EGRT bank 1, sensor 2 value is greater than a calibrated amount. |
Possible Causes
- Cooling System Concern
- Differential Pressure Feedback EGR Circuitry Concern
- Differential Pressure Feedback EGR Sensor Hose
- EGR Cooler
- EGR Valve
- Differential Pressure Feedback EGR Sensor
- Orifice tube assembly
- PCM