Volvo Engine Control Unit Fault Codes

Fault code explanation:

Water in Fuel

Fault indication:

DCU: Engine warning in DCU display.

CIU: Flash code

Flash code

Electrical fault: 2.9

Value fault: 2.1

Symptom:

None

Conditions for fault code:

Water in the fuel trap has been detected.

Suitable action:

1 Empty the water trap.

2 Check function of water in fuel switch

Measurements:

• Checking water in fuel switch page 119

Fault code explanation:

Faulty sensor / Faulty circuit

Fault indication:

DCU: Engine warning in DCU display.

CIU: Flash code

Flash code

Electrical fault: 2.9

Value fault: 2.1

Symptom:

None

Conditions for fault code:

The voltage signal on B8 is too high.

Possible reason:

The cable connected to B8 is short circuited to battery voltage.

Suitable action:

1 Check cable harness and connectors between water in fuel switch and

EMS 2.

Measurements:

• Checking supply cable, water in fuel switch page 118

• Checking negative cable, water in fuel switch page 118

Fault code explanation:

Faulty sensor / Faulty circuit

Fault indication:

DCU: Engine warning in DCU display.

CIU: Flash code

Flash code

Electrical fault: 2.9

Value fault: 2.1

Symptom:

None

Conditions for fault code:

The voltage signal on B8 is too low.

Possible reason:

• Short circuit between both cables to the water in fuel switch.

• The cable connected to B8 is short circuited to battery negative.

Suitable action:

1 Check cable harness and connectors between water in fuel monitor and

EMS 2.

Measurements:

• Checking supply cable, water in fuel switch page 118

• Checking negative cable, water in fuel switch page 118

Fault code explanation:

Oil pressure is too low

Fault indication:

DCU: Engine warning in DCU display

CIU: Flash code

Flash code

Electrical fault: 3.1

Value fault: 6.6

Symptom:

Power is reduced due to error torque map if engine protection parameter is

activated.

Conditions for fault code:

Oil pressure depends on the engine revolution. Oil pressure exceeds the set

value of the engine protection parameter

Possible reason:

• Too low engine oil level.

• Blocked oil filter.

• Oil leakage.

• Faulty oil pressure sensor.

Suitable action:

1 Check engine oil level and quality of the oil.

2 Change engine oil and oil filter to prevent blocked oil filter.

3 Check that no engine oil leakage occurs.

4 Check function of oil pressure sensor by control measuring the engine

oil pressure (see workshop manual Group 21-26).

Measurements:

• Checking oil pressure sensor page 121

Fault code explanation:

Faulty sensor / Faulty sensor circuit

Fault indication:

DCU: Engine warning in DCU display

CIU: Flash code

Flash code

Electrical fault: 3.1

Value fault: 6.6

Symptom:

None

Conditions for fault code:

The voltage on pin B11 on the EMS 2 is more than 4.95 Volt.

Possible reason:

• Short circuit between signal cable and 5V supply to oil pressure sensor.

• Faulty sensor.

Suitable action:

1 Check cable harness and connectors between oil pressure sensor and

EMS 2.

2 Check function of oil pressure sensor.

Measurements:

• Checking supply cable, oil pressure sensor page 119

• Checking negative cable, oil pressure sensor page 120

• Checking signal cable, oil pressure sensor page 120

• Checking oil pressure sensor page 121

Fault code explanation:

Faulty sensor / Faulty sensor circuit

Fault indication:

DCU: Engine warning in DCU display

CIU: Flash code

Flash code

Electrical fault: 3.1

Value fault: 6.6

Symptom:

None

Conditions for fault code:

The voltage on pin B11 on the EMS 2 is less than 0.07 Volt.

Possible reason:

• An open circuit in 5V supply cable to oil pressure sensor.

• An open circuit in signal cable to oil pressure sensor.

• Short circuit between signal cable and battery negative to oil pressure

sensor.

• Faulty sensor.

Suitable action:

1 Check contact pressure in socket 11 and 17 in engine connector B. Also

check contact pressure in connector at oil pressure sensor.

2 Check cable harness and connectors between oil pressure sensor and

EMS 2.

3 Check function of oil pressure sensor.

Measurements:

• Checking supply cable, oil pressure sensor page 119

• Checking negative cable, oil pressure sensor page 120

• Checking signal cable, oil pressure sensor page 120

• Checking oil pressure sensor page 121

Fault code explanation:

Inlet manifold temperature is too high

Fault indication:

DCU: Engine warning in DCU display

CIU: Flash code

Flash code

Electrical fault: 3.2

Value fault: 6.2

Symptom:

Engine is derated if engine protection parameter is activated.

Conditions for fault code:

Inlet manifold temperature exceeds the set value of the engine protection

parameter.

Possible reason:

• Engine temperature is too high.

• High surrounding temperature.

• Dust or dirt on the outside of the intercooler.

• Faulty inlet manifold temperature sensor.

Suitable action:

1 Check that engine temperature is normal.

2 Clean the intercooler.

3 Check function of inlet manifold temperature sensor.

Measurements:

• Checking inlet manifold temperature sensor page 124

Fault code explanation:

Faulty sensor / Faulty sensor circuit

Fault indication:

DCU: Engine warning in DCU display

CIU: Flash code

Flash code

Electrical fault: 3.2

Value fault: 6.2

Symptom:

Temperature is set to 40° C

Conditions for fault code:

The voltage on pin B47 on the EMS 2 is less than 0.07 Volt.

Possible reason:

• Short circuited sensor signal cable to battery negative.

• Faulty sensor.

Suitable action:

1 Check cable harness and connectors between inlet manifold temperature

sensor and EMS 2.

2 Check function of inlet manifold temperature sensor.

Measurements:

• Checking signal cable, inlet manifold temperature sensor page 121

• Checking negative cable, inlet manifold pressure/temperature

sensor page 122

• Checking sensor cable, inlet manifold temperature sensor page 123

• Checking inlet manifold temperature sensor page 124