Diagnosis and check 4.4L (Discovery 3)

Inspection and verification

WARNING: Be sure to wear eye protection when working with or in the vicinity of any fuel related items. Failure to follow this instruction may result in injury.

CAUTION: This procedure is related to fuel handling. Always be aware of the possibility of fuel splashing and observe fuel safety precautions. Failure to follow this instruction may result in injury.

WARNING: If swallowed, DO NOT induce vomiting. Seek immediate medical attention. Failure to follow this instruction may result in injury.

WARNING: If fuel gets in your eyes, rinse them with cold water or special eyewash solution and seek medical attention. Failure to follow this instruction may result in injury.

WARNING: Wash hands thoroughly after handling as prolonged contact may cause irritation. If irritation occurs, seek medical attention. Failure to follow this instruction may result in injury.

CAUTION: Before disconnecting any element of the fuel system, be sure to remove all dust and dirt around the elements to prevent dirt from entering the fuel system. Failure to follow this instruction may result in damage to the vehicle.

ATTENTION: Therefore, absolute cleanliness must be observed when working with these elements. Open holes or lines should always be plugged with appropriate plugs. Failure to follow this instruction may result in damage to the vehicle.

1. Make sure the customer's complaint is valid.

2. Visually inspect for obvious mechanical and electrical problems.

Mechanical factors	Electrical Factors
Fuel level Fuel contamination / fuel grade / fuel quality Fuel filter Fuel leaks Damaged fuel lines Damaged fittings Fuel filler cap Fuel tank filler line ROPS valves (ROV)	Charging and Battery Status Melting (e) fuse (And) Inertial fuel switch (IFS) Loose or corroded electrical connectors Wiring harnesses Fuel pump relay fuel pump module Engine control module (ECM)

3. If an obvious cause of a problem you identified or described by a customer is found, resolve it before proceeding to the next steps (if possible).


4. Use an approved diagnostic system or scan tool (tester), to retrieve all DTCs before referring to the symptom table or DTC index (DTC).

Clear all DTCs after troubleshooting.

Symptom table

Symptom	Possible reasons	Action
Engine cranks but won't start	Inertial fuel switch (IFS) Low/contaminated fuel Disconnecting / reducing the capacity of the engine ventilation system Ignition system fuel leak Clogged fuel filter Fuel Pump Module Malfunction crankshaft position sensor (CKP) ECM malfunction	Check if the inertial switch is activated. Check fuel level/condition. Check engine ventilation system. Check for ignition system related DTCs Check the fuel system for leaks/damage. Check fuel filter for blockage/reduced flow. Check the operation of the fuel pump module. Check the CKP sensor. Refer to the relevant section in the workshop manual. If there is any doubt about the functionality of the module, refer to the Warranty Policy and Procedures Manual.
Engine cranks and flashes but won't start	EVAP canister purge valve Low fuel pressure fuel leak Clogged fuel filter Fuel Pump Module Malfunction Spark plug Short to ground in high voltage electrical circuit (breakdown). Check rubber boots for cracks/damage Ignition coil failure Wiring harness	Check the evaporative emission system purge valve. Check the pressure in the fuel system. Check the fuel system for leaks/damage. Check the fuel filter for blockage/reduced flow. Check the operation of the fuel pump module. Check spark plugs and ignition coils. Refer to the relevant section in the workshop manual.
Difficulty starting after a hot soak (the vehicle is aged after the engine has reached operating temperature)	Nozzle leak Fuel temperature sensor Air intake temperature sensor (IAT) Mass air flow sensor (MAF) EVAP canister purge valve Fuel Pump Module Malfunction Ignition system	Check the injectors. Check fuel temperature sensor circuits, IAT and MAF. Check the evaporative emission system purge valve. Check the operation of the fuel pump module. Check spark plug and ignition coil circuits. Refer to the relevant section in the workshop manual.
Engine stalls shortly after starting	Disconnection / reduction of ventilation system capacity ECM relay Wiring harness MAF sensor Ignition system Clogged air filter Air leak Fuel lines Fuel rail pressure sensor (FRP)	Check engine ventilation system. Check the ECM relay and circuits. Check MAF sensor circuits. Check spark plug and ignition coil circuits. Check for clogged air filter. Check air intake system for leaks. Check fuel lines for leaks/damage. Check the electrical circuits of the FRP sensor. Refer to the relevant section in the workshop manual.
Engine acceleration lag/poor acceleration	Difficulty moving the pedal (flooring, etc.) EGR valve sticking (EGR) in the open position Ignition system Air leak Heated oxygen sensors (HO2S) Fuel pressure Clogged fuel filter Fuel lines Fuel Pump Module Malfunction Nozzle leak Throttle Position Sensors (TR) Throttle motor Accelerator pedal position sensor (APP) Transmission malfunction	Check the movement of the accelerator pedal. Check spark plug and ignition coil circuits. Check air intake system for leaks. Check the HO2 sensor circuits. Check the pressure in the fuel system. Check the fuel filter for blockage/reduced flow. Check the fuel system for leaks/damage.
Backfires in the engine.	Ignition system Air leak Fuel lines Fuel Pump Module Malfunction MAF sensor HO2 sensors APP sensor	Check spark plug and ignition coil circuits. Check air intake system for leaks. Check the fuel system for leaks/damage. Check the operation of the fuel pump module. Check MAF, HO2 and APP sensor circuits. Refer to the relevant section in the workshop manual.
Engine Jerks	Fuel lines Fuel Pump Module Malfunction MAF sensor Wiring harness TP sensors Throttle motor Ignition system ECM malfunction	Check the fuel system for leaks/damage. Check the operation of the fuel pump module. Check the circuits of the MAF sensor, TP sensor and throttle motor. Check ignition coil circuits. Refer to the relevant section in the workshop manual. If there is any doubt about the functionality of the module, refer to the Warranty Policy and Procedures Manual.
Detonation / knocking in the engine	Fuel quality Fuel lines Fuel Pump Module Malfunction Air leak FRP sensor Knock sensor malfunction (KS) / electrical circuit MAF sensor HO2 sensors BARO sensor malfunction (internal ECM malfunction)	Check the fuel for contamination, as well as the brand and quality of the fuel. Check the fuel system for leaks/damage. Check the operation of the fuel pump module. Check air intake system for leaks. Check the FRP, KS, MAF and HO2 sensor circuits. Refer to the relevant section in the workshop manual. If there is any doubt about the functionality of the module, refer to the Warranty Policy and Procedures Manual.

DTC index

NOTE: Universal Scan Tools cannot read the listed codes or can only read 5-digit codes. Match the 5 digits from the scan tool with the first 5 digits of the listed 7 digit code to identify the problem (the last 2 digits give additional information read by the diagnostic system approved by the manufacturer).

NOTE: See Section 303-14 for a complete list of ECM DTCs "Electronic engine management system" in the workshop manual.

DTC	Description	Possible reasons	Action
P017100	Too much lean in the system (cylinder bank 1)	Air intake leak between MAF sensor and cylinder head MAF sensor malfunction (low air intake flow) Low fuel pressure Reducing the capacity of the fuel filter / fuel system Fuel Pump Module Malfunction Reduced fuel injector capacity Leak in the exhaust system (before the catalytic converter) Evaporative Emission System Malfunction	Check air intake system for leaks. Check circuits and MAF sensor. Check the pressure in the fuel system. Check fuel filter for blockage/reduced flow. Check the fuel system for leaks/damage. Check the operation of the fuel pump module. Check the injectors. Check the exhaust system for leaks, etc. Refer to the relevant section in the workshop manual. Check for DTCs for the evaporative emission system
P017200	Too much enrichment in the system (cylinder bank 1)	Reducing the capacity of the air filter High fuel pressure Fuel injector leak (Oh) Oil contamination with fuel (too many cold starts without bringing the car up to a high enough temperature for a long enough time) MAF sensor malfunction Evaporative Emission System Malfunction	Check the air intake system for blockage. Check fuel system for leaks, check fuel pressure. Check the injectors. Check for DTCs related to the fuel system. Check the cleanliness/grade/quality of the oil Refer to the appropriate section in the workshop manual. Check for DTCs for the MAF sensor and the evaporative emission system.
P017400	Too much lean in the system (cylinder bank 2)	Air intake leak between MAF sensor and cylinder head MAF sensor malfunction (low air intake flow) Reducing the capacity of the fuel filter / fuel system Low fuel pressure Reduced fuel injector capacity Leak in the exhaust system (before the catalytic converter) Evaporative Emission System Malfunction	Check the air intake system for leaks, etc. Check the fuel system for reduced capacity, DTCs, etc. Check the exhaust system for leaks, etc. Refer to the relevant section in the workshop manual. Check for DTCs for the evaporative emission system.
P017500	Too much enrichment in the system (cylinder bank 2)	Reducing the capacity of the air filter High fuel pressure Fuel injector leak (Oh) Oil contamination with fuel (too many cold starts without bringing the car up to a high enough temperature for a long enough time) MAF sensor malfunction Evaporative Emission System Malfunction	Check the air intake system for reduced capacity, etc. Check the fuel system for leaks, DTCs, etc. Check the condition of the oil. Refer to the relevant section in the workshop manual. Check for DTCs for the MAF sensor and the evaporative emission system.
P030000	Accidental misfire reported	Malfunctions in the low voltage electrical circuit from the ECM to the ignition coil (Cylinder Misfire DTCs also registered) Ignition coil failure Faulty/dirty/incorrect spark plug gap Fuel supply pressure (low / high) Malfunction (And) fuel injector electrical circuit (injector DTCs also logged) Decrease in capacity/leakage in fuel injectors Fuel injectors permanently open Fuel contamination Low compression in the engine cylinder Valve clearance adjustment Camshaft wear/broken valve springs	Check for DTCs related to the ignition coil. Check the condition and gaps of the spark plugs. Check the pressure in the fuel system. Check for injector related DTCs. Check the fuel for contamination, as well as the brand and quality of the fuel. Check the compression in the engine cylinders, check the valve clearances, check the condition of the camshaft and valve springs. Refer to the relevant section in the workshop manual.
P046129	Fuel Level Sensor A Circuit Range/Performance Problems	Fuel Level Sensor Circuits Intermittent Short or High Resistance Fuel Level Sensor Malfunction	Check the fuel sensor circuit according to the electrical manual. Repair/replace as needed.
P04612F	Fuel Level Sensor A Circuit Range/Performance Problems	Fuel Level Sensor Circuits Intermittent Short or High Resistance Fuel Level Sensor Malfunction	Check the fuel sensor circuit according to the electrical manual. Repair/replace as needed.
P046200	Fuel Level Sensor Circuit A Low Voltage Input	Fuel level sensor circuits intermittent short to ground or high resistance Fuel Level Sensor Malfunction	Check the fuel sensor circuit according to the electrical manual. Repair/replace as needed.
P046300	Fuel Level Sensor A Circuit High Input Voltage	Fuel level sensor circuits - intermittent short to + battery Fuel Level Sensor Malfunction	Check the fuel sensor circuit according to the electrical manual. Repair/replace as needed.
P062800	Fuel Pump A Control Circuit Low Voltage	Fuel pump control circuit short to ground Fuel pump control circuit high resistance Fuel pump relay malfunction	Refer to the electrical manual and check the fuel pump electrical circuits. Activate the relay and listen to "click". Repair/replace as needed. Clear DTCs and check for correct operation.
P062900	High voltage in the fuel pump A control circuit	Fuel pump control circuit short to battery Fuel pump relay malfunction	Refer to the electrical manual and check the fuel pump electrical circuits. Activate the relay and listen to "click". Repair/replace as needed. Clear DTCs and check for correct operation.
P131500	Resistant misfire	Malfunction in the low voltage electrical circuit from the ECM to the ignition coil (Cylinder Misfire DTC also registered) Ignition coil failure Faulty/dirty/incorrect spark plug gap Low fuel pressure Malfunction (And) fuel injector electrical circuit (injector DTCs also logged) Fuel contamination Low compression in the engine cylinder	Check for DTCs related to the ignition coil. Check the condition and gaps of the spark plugs. Check the pressure in the fuel system. Check for injector related DTCs. Check the fuel for contamination, as well as the brand and quality of the fuel. Check the compression in the cylinders. Refer to the relevant section in the workshop manual.