Diagnostics and testing 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 ducts (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 Charge air coolers (damage/connection)	Mass Air Flow (MAF) Sensor Manifold Absolute Pressure (MAP) Sensor Manifold Absolute Pressure and Temperature (MAPT) Sensor Throttle body Wiring harness (fastening/damage) Connections (fastening/damage)

3. If an obvious cause for the problem you identified or the customer described is found, resolve it before moving on to further action. (if possible).

4. Before referring to the Symptom Chart or DTC Index, read all DTCs using an approved diagnostic system or scan tool.

Clear all DTCs after troubleshooting.

Table of signs of malfunction

Sign of malfunction	Possible reasons	Action
Engine does not start/difficult to start/poor dynamic characteristics	Reduced air flow/blockage of the air intake system Reduced flow rate/filter element clogging	Eliminate the cause of the decrease in air flow. If necessary, replace the air filter element. Refer to the relevant section in the service station manual.
Increased noise at intake	Disconnection/damage to intake manifold after air filter Air filter assembly incorrectly assembled/damaged	Check the air intake system and hoses for proper installation/damage. Refer to the relevant section in the workshop manual.
Insufficient boost	Mechanical compressor drive belt is broken/slipping Mechanical compressor failure Mechanical compressor air intake malfunction Large air leak (after mechanical compressor)	Check the mechanical compressor and drive belt. Check the charge air coolers. Refer to the appropriate section in the workshop manual.
Noise	Mechanical compressor drive belt slippage Mechanical compressor failure Large air leak (after mechanical compressor)	Check the mechanical compressor and drive belt. Remove the mechanical compressor drive belt and recheck for noise. Rotate the mechanical compressor by hand and check for increased resistance. Check for increased clearance in the mechanical compressor pulley. Check the charge air coolers. Refer to the appropriate section in the workshop manual.

DTC Index

NOTE: Generic scan tools may not be able to read the codes listed or may only be able to 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 fault. (the last 2 digits provide additional information readable by an approved diagnostic system).

NOTE: For a complete list of ECM DTCs, refer to Section 303-14 - Electronic Engine Controls in the service manual.

DTC	Description	Possible reasons	Action
P010100	Electrical circuit for mass or volume air flow A	Clogged air filter Leak in the air intake Leak in the engine ventilation system Mass Air Flow (MAF) Sensor Signal Circuit High Resistance, Intermittent Short to Ground MAF Sensor Power Circuit High Resistance	Check the air filter for blockages, etc. Check the air intake system for leaks. Check the engine ventilation system. Refer to the appropriate section in the workshop manual. Refer to the guided diagnostic routine for this code on the approved diagnostic system.
P010600	Manifold Absolute Pressure/BARO Sensor Range/Performance Problems	Air leak in the intake manifold (loose or missing element) Malfunction in the electrical circuit(s) of the MAP sensor MAP sensor malfunction	Check intake manifold for looseness, etc. Refer to the guided diagnostic routine for this code on the approved diagnostic system.
P017100	Too much leanness in the system (cylinder bank 1)	Leak in the air intake system between the MAF sensor and the cylinder head MAF sensor malfunction (low intake air flow) Reduced fuel filter/fuel system flow capacity Low fuel pressure Clogged fuel injector Leak in the exhaust system (before the catalytic converter) Fuel Evaporative Emissions Control System Malfunction	Check the air intake system for leaks, etc. Check the fuel system for reduced flow, DTCs, etc. Check the exhaust system for leaks, etc. Check for DTCs for the evaporative emission control system
P017200	Too much enrichment in the system (cylinder bank 1)	Reducing the air filter capacity High fuel pressure Leaking fuel injector(s) Oil contamination with fuel (too many cold starts without allowing the vehicle to reach a high enough temperature for a sufficiently long time) MAF sensor malfunction Fuel Evaporative Emissions Control System Malfunction	Check the air intake system for restriction, etc. Check the fuel system for leaks, DTCs, etc. Check the oil condition. Check for DTCs for the MAF sensor and the evaporative emission control system.
P017400	Too much leanness in the system (cylinder bank 2)	Leak in the air intake system between the MAF sensor and the cylinder head MAF sensor malfunction (low intake air flow) Reduced fuel filter/fuel system flow capacity 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 flow, DTCs, etc. Check the exhaust system for leaks, etc. Check for DTCs for the evaporative emission control system.
P017500	Too much enrichment in the system (cylinder bank 2)	Reducing the air filter capacity High fuel pressure Leaking fuel injector(s) Oil contamination with fuel (too many cold starts without allowing the vehicle to reach a high enough temperature for a sufficiently long time) MAF sensor malfunction Fuel Evaporative Emissions Control System Malfunction	Check the air intake system for restriction, etc. Check the fuel system for leaks, DTCs, etc. Check the oil condition. Check for DTCs for the MAF sensor and the evaporative emission control system.
P050600	Crankshaft speed with air supply management system in idle mode is lower than expected	Reducing the air intake capacity Auxiliary drive overload (defective/sticking element)	Check the air intake system. Check the accessory drive belt and components. Refer to the appropriate section in the workshop manual.
P050700	Crankshaft speed with air supply management system in idle mode is higher than expected	Leak in the air intake system between the mass air flow (MAF) sensor and the throttle valve Leak in the air intake system between the throttle valve and the engine Leak in the engine crankcase ventilation system	Check the air intake system. Check the engine ventilation system. Refer to the relevant section in the service station manual.
P066100	Intake Manifold Tuning Valve Control Circuit Low Voltage - Bank 1	Variable Air Intake System Adjustment Valve Control Circuit: Short to Ground Malfunction of the air intake system adjustment valve	Check the air intake system tuning valve and electrical circuits. Refer to the electrical manual. If no fault is found in the electrical circuits, install a new air intake system tuning valve. Clear DTCs and check for proper operation.
P066200	Intake Manifold Tuning Valve Control Circuit High Voltage - Bank 1	Electrical circuit for control of the adjustable air intake system adjustment valve: short circuit to +battery Malfunction of the air intake system adjustment valve	Check the air intake system tuning valve and electrical circuits. Refer to the electrical manual. If no fault is found in the electrical circuits, install a new air intake system tuning valve. Clear DTCs and check for proper operation.
P207000	Intake Manifold Tuning Valve Stuck Open - Bank 1	Electrical circuit for control of the adjustable air intake system adjustment valve: short circuit to +battery Malfunction of the air intake system adjustment valve	Check the air intake system tuning valve and electrical circuits. Refer to the electrical manual. If no fault is found in the electrical circuits, install a new air intake system tuning valve. Clear DTCs and check for proper operation.
P207100	Intake Manifold Tuning Valve Stuck Open - Bank 2	Electrical circuit for control of the adjustable air intake system adjustment valve: short circuit to +battery Malfunction of the air intake system adjustment valve	Check the air intake system tuning valve and electrical circuits. Refer to the electrical manual. If no fault is found in the electrical circuits, install a new air intake system tuning valve. Clear DTCs and check for proper operation.