Diagnostics and testing 4.4L (Discovery 3)

Inspection and verification

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

2. Perform a visual inspection 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	Mass Air Flow (MAF) Sensor Manifold Absolute Pressure (MAP) 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, correct 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 index.

Clear all DTCs after troubleshooting.

Table of signs of malfunction

Sign of malfunction	Possible reason	Operation
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 throughput. If necessary, replace the air filter element.
Increased noise at intake	Disconnection/damage to the intake manifold after the air filter Air filter assembly incorrectly assembled/damaged	Check the air intake system and hoses for proper installation/damage.

DTC Index

NOTE: Generic scan tools cannot read the codes listed 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 fault. (the last 2 digits provide additional information readable by a manufacturer approved diagnostic system).

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

DTC	Description	Possible reasons	Operation
P010100	Electrical circuit for mass or volume air flow A	Clogged air filter Leak in the air intake Engine ventilation leak 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 of 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 air intake flow) Reduced fuel filter/system flow capacity Low fuel pressure Reducing fuel injector flow Leak in the exhaust system (before the catalytic converter) Fuel vapor recovery system malfunction	Check the air intake system for leaks, etc. Check the fuel system for reduced throughput, DTC, etc. Check the exhaust system for leaks, etc. Check for DTC codes for the fuel vapor capture 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 warming up for a sufficiently long time) MAF sensor malfunction Fuel vapor recovery 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 evaporative emission 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 air intake flow) Reduced fuel filter/system flow capacity Low fuel pressure Reducing fuel injector flow Leak in the exhaust system (before the catalytic converter) Fuel vapor recovery 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 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 warming up for a sufficiently long time) MAF sensor malfunction Fuel vapor recovery 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 evaporative emission system.
P050600	Crankshaft speed with air supply management system in idle mode is lower than expected	Clogged air intake Auxiliary drive overload (defective/sticking element)	Check the air intake system. Check the accessory drive belt and components. Refer to the relevant section of 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 engine crankcase ventilation	Check the air intake system. Check the engine ventilation system. See the relevant section of the service station manual.