DTC 1-5-4

1-5-4 EGR SYSTEM LEAKAGE




Trouble Code Conditions
If the Engine Control Module (ECM) notes that the EGR temperature sensor has changed by more than 60 mV before the Engine Coolant Temperature (ECT) Sensor has reached 60°C (140°F), the ECM interprets it as an EGR flow occurring when it should not, and Diagnostic Trouble Code (DTC) 1-5-4 is set.

Substitute value(s)
- None.

Fault source(s)
- EGR vacuum controller signal lead short circuit to ground.
- Defective vacuum lead.
- Defective EGR vacuum controller.
- Defective EGR valve.
- Contact resistance in EGR temperature sensor circuit.
- Defective thermostat in engine cooling system.

NOTE: If engine does not reach working temperature within a given time, the engine compartment temperature can affect the EGR temperature sensor sufficiently to change the signal to the ECM by more than 60 mV.

Fault symptom(s)
- Engine idles unevenly.

TEST PROCEDURE




CHECK IDLE
- Start engine and listen to engine at idle.

If engine idles unevenly:
^ Check EGR-vacuum controller signal lead. Proceed to CHECK EGR-VACUUM CONTROLLER SIGNAL LEAD procedure below.

If engine idles evenly:
^ Check engine temperature. Proceed to CHECK ENGINE TEMPERATURE procedure below.




CHECK EGR-VACUUM CONTROLLER SIGNAL LEAD
- Engine at idle.
- Disconnect EGR-vacuum controller.

If engine continues to idle unevenly:
^ Check EGR-vacuum controller. Proceed to CHECK EGR-VACUUM CONTROLLER procedure below.

If engine then idles evenly:
^ Check lead between EGR-vacuum controller connection 2 and ECM # 33 for short circuit to ground.




CHECK EGR-VACUUM CONTROLLER
- Engine at idle.
- Carefully remove the yellow hose from the EGR-vacuum controller.

If engine continues to idle unevenly:
^ Check EGR-valve. Proceed to CHECK EGR-VALVE procedure below.

If engine then idles evenly:
^ Test with new EGR-vacuum controller.




CHECK EGR-VALVE
- Engine at idle.
- Carefully remove the yellow hose from the EGR-valve.

Warning: EGR-valve can be hot.

If engine continues to idle unevenly:
^ Test with new EGR-valve.

If engine then Idles evenly:
^ Check whether yellow hose is blocked. Replace if necessary.




CHECK ENGINE TEMPERATURE
- Engine at idle.
- Enter DTC parameter list.
- Check whether engine temperature is rising and that it is at normal level.

If engine temperature rises normally:
^ Fix EGR-temperature sensor connector for contact resistance and oxidation.
^ After fixing: Proceed to INTERMITTENT FAULT procedure below.

If ECT sensor does not rise sufficiently:
^ Test with new thermostat.




INTERMITTENT FAULT
- Check whether EGR-vacuum controller functions are correctly using Diagnostic Test Mode (DTM) 3.
- Using a vacuum pump, check that EGR-valve is not binding.
- Check 55-pin connector in central relay unit (A3/D) connection 8 and 12 for contact resistance and oxidation.
- Check lead between EGR-vacuum controller connection 2 and ECM # 33 for intermittent short circuit to ground.