Diagnosis and check 4.0L (Discovery 3)

Inspection and verification

1. Check the validity of the customer's complaint.

2. Visually inspect for obvious signs of damage.

Mechanical factors	Electrical Factors
Hoses and air lines (damage / connections) Air filter element (contamination / blockage) Reducing the capacity of the air intake system mechanical compressor Mechanical compressor drive belt (cooling fan) Mechanical compressor seals and gaskets Air coolers (damage / connection)	Mass air flow sensor (MAF) Manifold absolute pressure sensor (MAP) Manifold absolute pressure and temperature sensor (MAPT) throttle body Wiring harness (fastening / damage) Connections (fastening / damage)

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. Read all DTCs using an approved diagnostic system or scan tool before referring to the Symptom Chart or DTC Index.

Clear all DTCs after troubleshooting.

Symptom table

Symptom	Possible reasons	Action
Engine won't start/difficult to start/poor performance	Decrease in capacity / blockage of the air intake system Reduced throughput / blockage of the filter element	Correct the cause of the reduced throughput. Replace the air filter element if necessary. Refer to the relevant section in the workshop manual.
Increased intake noise	Detachment/damage of the inlet pipeline after the air filter Air filter assembly incorrectly assembled/damaged	Check the air intake system and hoses for correct installation/damage. Refer to the relevant section in the workshop manual.
Insufficient boost	Mechanical compressor drive belt broken/slipping Mechanical compressor failure Malfunction of the air intake of a mechanical compressor Large air leak (after mechanical compressor)	Check mechanical compressor and drive belt. Check charge air coolers. Refer to the relevant section in the workshop manual.
Noise	Mechanical compressor drive belt slip Mechanical compressor failure Large air leak (after mechanical compressor)	Check mechanical compressor and drive belt. Remove the mechanical compressor drive belt and recheck for noise. Turn the mechanical compressor by hand and check for increased resistance. Check for excessive play in the mechanical compressor pulley. Check charge air coolers. Refer to the relevant section in the workshop manual.

DTC index

NOTE: Universal Scan Tools may not read the listed codes or may 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 approved diagnostic system).

NOTE: For a complete list of ECM DTCs, refer to Section 303-14 - "Electronic engine controls" in the workshop manual.

DTC	Description	Possible reasons	Action
P010100	Mass or volume air flow circuit A	Air filter blockage Air intake leak Leak in engine ventilation system Mass Air Flow Sensor Signal Circuit (MAF): high resistance, intermittent short circuit to ground MAF sensor supply circuit high resistance	Check the air filter for clogging, etc. Check the air intake system for leaks. Check engine ventilation system. Refer to the relevant section in the workshop manual. Refer to the guided diagnostic program for this code on the approved diagnostic system.
P010600	Manifold Absolute Pressure Sensor/BARO Range/Performance Issues	Air leak in intake manifold (loose or missing item) Malfunction in the electrical circuit (I) MAP sensor MAP sensor malfunction	Check the tightness of the intake manifold, etc. Refer to the guided diagnostic program for this code on the approved diagnostic system.
P017100	Too much lean in the system (cylinder bank 1)	Air intake leak between MAF sensor and cylinder head MAF sensor malfunction (low intake air flow) Reducing the capacity of the fuel filter / fuel system Low fuel pressure Clogged fuel injector Leak in the exhaust system (before the catalytic converter) Malfunction of the fuel vapor control system	Check the air intake system for leaks, etc. Check the fuel system for reduced capacity, DTCs, etc. Check the exhaust system for leaks, etc. Check for DTCs for the fuel vapor control 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 Malfunction of the fuel vapor control system	Check the air intake system for reduced capacity, etc. Check the fuel system for leaks, DTCs, etc. Check the condition of the oil. Check for DTCs for the MAF sensor and the fuel vapor control system.
P017400	Too much lean in the system (cylinder bank 2)	Air intake leak between MAF sensor and cylinder head MAF sensor malfunction (low intake air flow) Reducing the capacity of the fuel filter / fuel system Low fuel pressure Clogged fuel injector Leak in the exhaust system (before the catalytic converter)	Check the air intake system for leaks, etc. Check the fuel system for reduced capacity, DTCs, etc. Check the exhaust system for leaks, etc. Check for DTCs for the fuel vapor control 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 Malfunction of the fuel vapor control system	Check the air intake system for reduced capacity, etc. Check the fuel system for leaks, DTCs, etc. Check the condition of the oil. Check for DTCs for the MAF sensor and the fuel vapor control system.
P050600	The speed of rotation of the crankshaft, taking into account the air supply control system in idle mode, is lower than expected	Reducing the air intake capacity Accessory Drive Overload (defective/jamming element)	Check the air intake system. Check accessory drive belt and components. Refer to the relevant section in the workshop manual.
P050700	The speed of rotation of the crankshaft, taking into account the air supply control system in idle mode, is higher than expected	Leakage in the air intake system between the mass air flow sensor (MAF) and throttle valve Air intake leak between throttle and engine Leakage in the crankcase ventilation system	Check the air intake system. Check engine ventilation system. Refer to the relevant section in the workshop manual.
P066100	Intake manifold trim valve control circuit low - bank 1	Variable Intake Air Adjustment Valve Control Circuit Short to Ground Air intake adjustment valve malfunction	Check air intake adjustment valve and electrical circuits. Refer to the electrical manual. If no electrical fault is found, install a new air intake adjustment valve. Clear the DTCs and check for correct operation.
P066200	High voltage in the intake manifold trim valve control circuit - bank 1	Variable Air Intake System Adjustment Valve Control Circuit Short to Battery Air intake adjustment valve malfunction	Check air intake adjustment valve and electrical circuits. Refer to the electrical manual. If no electrical fault is found, install a new air intake adjustment valve. Clear the DTCs and check for correct operation.
P207000	Intake manifold adjustment valve stuck open - bank 1	Variable Air Intake System Adjustment Valve Control Circuit Short to Battery Air intake adjustment valve malfunction	Check air intake adjustment valve and electrical circuits. Refer to the electrical manual. If no electrical fault is found, install a new air intake adjustment valve. Clear the DTCs and check for correct operation.
P207100	Intake manifold adjustment valve stuck open - bank 2	Variable Air Intake System Adjustment Valve Control Circuit Short to Battery Air intake adjustment valve malfunction	Check air intake adjustment valve and electrical circuits. Refer to the electrical manual. If no electrical fault is found, install a new air intake adjustment valve. Clear the DTCs and check for correct operation.