Diagnostics and testing 2.7L (Discovery 3)

Inspection and verification

1. Ensure that the customer's complaint is justified.

2. Visually inspect for obvious mechanical and electrical problems.

Mechanical factors	Electrical factors
Engine oil level Coolant level Fuel level Fuel contamination/fuel brand/fuel quality Fuel leaks Auxiliary drive belt Installation/sensor status Fan with viscous coupling and electromagnetic valve	Fuses and fuses Wiring harness Electrical connector(s) Sensor power supply 5V Sensor(s) Engine Control Module (ECM) Transmission Control Module (TCM)

3. If an obvious cause for the problem you identified or the customer described is found, resolve it before proceeding with further actions. (if possible).

4. Use the approved diagnostic system or scan tool to retrieve all diagnostic trouble codes (DTCs) before referring to the symptom chart or dTc indicator.

Clear all DTCs after troubleshooting.

Table of signs of malfunction

Sign of malfunction	Possible reasons	Actions
The engine turns over but does not start	Inertia Fuel Switch (IFS) Low fuel level/contamination Air leak Low pressure in the fuel system Fuel pump module malfunction Fuel filter clogged Clogged/contaminated fuel control valve (VCV) Clogged/contaminated fuel pressure valve (FPCV) High pressure fuel pump malfunction Crankshaft Position Sensor (CKP) ECM failure	Check if the inertia switch is activated. Check the fuel level/condition. Check the air intake system for leaks. Check the operation of the fuel pump module, check the low pressure circuit of the fuel system for leaks/ damage. Check the fuel filter, check the VCV and FPCV. Check the high-pressure fuel pump. Refer to the corresponding section in the service station manual. Check the electrical circuits of the SCR sensor. Refer to the electrical equipment manual. If a module is suspected, please refer to the Warranty Service Policies and Procedures manual.
Difficulty starting	Malfunction of the glow plug system (very low temperature conditions) Low fuel level/contamination Air leak Fuel pump module malfunction Low pressure in the fuel system Fuel filter clogged Clogged/contaminated fuel control valve (VCV) Clogged/contaminated fuel pressure valve (FPCV) Exhaust Gas Recirculation (EGR) Valve(s) Malfunction	Check glow plug electrical circuits. Check fuel level/condition. Check air intake system for leaks. Check fuel pump module operation, check low pressure fuel system circuit for leaks/damage. Check fuel filter, check VCV and FPCV. EGR valve checks are described in the relevant section of the workshop manual.
Rough idle operation	Air intake Low fuel level/contamination Low pressure in the fuel system Fuel filter clogged Clogged/contaminated fuel control valve (VCV) Clogged/contaminated fuel pressure valve (FPCV) Exhaust Gas Recirculation (EGR) Valve(s) Malfunction	Check the air intake system for leaks. Check the fuel level/condition. Check the low pressure fuel system circuit for leaks/damage. Check the fuel filter, check the VCV, FPCV and EGR valve, for checks, refer to the relevant section of the workshop manual.
Loss of power when accelerating	Air intake system malfunction Clogged exhaust system Low fuel pressure Exhaust Gas Recirculation (EGR) Valve(s) Malfunction Variable Gate Turbocharger (VGT) actuator failure	Check the air intake system. Check the exhaust system for leaks or blockages. Install new components if necessary. Check the fuel system pressure. Checks of the EGR valve and VGT actuator are described in the relevant section of the service station manual.
Engine stops/stalls	Air leak Low fuel level/contamination Low pressure in the fuel system High pressure fuel leak Clogged/contaminated fuel control valve (VCV) Clogged/contaminated fuel pressure valve (FPCV) Exhaust Gas Recirculation (EGR) Valve Malfunction	Check the air intake system for leaks. Check the fuel level/condition. Check the fuel system for leaks/damage. Check the fuel system for leaks, check the VCV and FPCV. EGR valve checks are described in the relevant section of the workshop manual.
Engine jerking	Low fuel level/contamination Air intake Low pressure in the fuel system Blocked/contaminated fuel metering valve Clogged/contaminated fuel control valve (VCV) Clogged/contaminated fuel pressure valve (FPCV) High pressure fuel leak High pressure fuel pump malfunction	Check the fuel level/ condition. Check the air intake system for leaks. Check the fuel system low pressure circuit for leaks/ damage. Check the high-pressure fuel system for leaks, check the VCV and FPCv. Check the high-pressure fuel pump. Refer to the corresponding section in the service station manual.
Excessive fuel consumption	Low pressure in the fuel system Clogged/contaminated fuel control valve (VCV) Clogged/contaminated fuel pressure valve (FPCV) Leak in fuel temperature sensor High pressure fuel leak Injector malfunction (ok) Exhaust Gas Recirculation (EGR) Valve(s) Malfunction	Check the low pressure fuel system circuit for leaks/damage. Check the VCV and FPCV, fuel temperature sensor, high pressure fuel pump, etc. for leaks. Refer to the relevant section in the workshop manual. Check for injector DTCs. EGR valve tests are described in the relevant section of the workshop manual.