DTC 1-5-4

1-5-4 EXHAUST GAS RECIRCULATION SYSTEM LEAKAGE

Condition(s) for DTC
^ Engine cold (temperature below 65°C / 150°F).
^ Rising temperature sensor indication (falling signal level).
^ If the ICM detects that the EGR temperature sensor signal level is varying by more than the predetermined (temperature-dependent) values before the engine temperature has reached 65°C (150°F), it will interpret the condition as indicating an EGR flow when none should be present, and the DTC will be recorded.

Substitute value
^ None.

Fault source(s)
^ Faulty (leaking) EGR valve.
^ Faulty signal to EGR controller.
^ Faulty EGR controller.
^ Poor ground connection.
^ Faulty coolant thermostat.

Fault symptom(s)
^ Engine may idle unevenly.

NOTE: Take care when removing the yellow and white hoses. Grip and twist hose rubber connector ends only, not the plastic hose itself. The hoses may break or crack if pulled from their connections.

TESTING PROCEDURE





Status message
^ Check current Status Message.

If Status message is: Leakage.
- Proceed to: Checking engine idling Section below.





Checking engine idling
^ START engine and listen to sound.

If engine idles unevenly:
- Check signal lead.
If engine idles evenly:
- Check engine temperature.





Checking signal lead
^ IDLE engine.
^ Disconnect EGR controller.

If engine continues to idle unevenly:
- Check EGR controller.
If engine now idles evenly:
- Check lead between ICM A27 and EGR controller connector terminal 1 for short-circuit.





Checking EGR controller
^ IDLE engine.
^ Carefully disconnect yellow hose (vacuum hose between EGR controller and EGR valve) from controller.

If engine continues to idle unevenly:
- Check yellow hose.
If engine now idles evenly:
- Try with new EGR controller.





Checking yellow hose
^ IDLE engine.

CAUTION! EGR valve may be hot.

^ Carefully disconnect yellow hose at EGR valve.

If engine continues to idle unevenly:
- Try with new EGR valve.
If engine now idles evenly:
- Check if yellow hose is blocked or leaking.
- Replace hose as required.





Checking engine coolant temperature
^ START engine and run up to working temperature.
^ Display DTC parameter list.
^ Read engine coolant temperature.
^ Check that:
- Engine temperature rises normally;
- Volvo ST indicates normal working temperature and upper coolant hose is hot.

If ST indicates normal working temperature and upper coolant hose is hot:
- Check connectors.
If ST indication rises slowly and upper hose does not reach normal temperature:
- Try with new coolant thermostat.
If ST indication does not rise to normal working temperature but upper coolant hose is hot:
- Check control module signal grounds





Checking control module signal grounds
^ Switch OFF ignition.
^ Disconnect MAF sensor.
^ Connect ohmmeter between MAF sensor connector terminal 2 and ground.

Instrument should indicate approx. 0 Ohms.

If reading is correct:
- Check connector.
If reading is incorrect:
- Disconnect ground terminal 31/33 (under intake manifold on cylinder block).
- Clean and reassemble terminal.





Checking connectors
^ DTC may be due to contact resistance in EGR and ECT sensor connectors.
^ Clean and treat connectors to protect against oxidation.