Diagnostics and testing 2.7L (Discovery 3)

Contents: Inspection and verification ⇩ Table of signs of malfunction ⇩ DTC Index ⇩

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 ventilation hoses Oil separator EGR pipes (checking for cracks) EGR valve(s) EGR heat exchanger(s)	Fuse(s) Wiring harness Loose or corroded connector(s) Air Intake Throttle Valve EGR valve(s) Engine Control Module (ECM)

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. 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 (specific)	Possible reason	Action
Difficulty starting Uneven / erratic idle operation Loss of power when accelerating	EGR valve stuck open.	Check the EGR valve.
Engine stops/stalls	EGR valve stuck open. Disconnection/reduction in flow capacity/blockage of ventilation system	Check the EGR valve. Check the engine ventilation system. Check the oil separator. Check for EGR related DTCs.
Increased fuel consumption Increased amount of black smoke Increased emission of contaminants	EGR valve stuck open. EGR not working Reduced throughput/blockage of ventilation system	Check the EGR valve. Check the engine ventilation system. Check the oil separator. Check for EGR related DTCs.
Increased gas breakthrough	Reduced throughput/blockage of ventilation system	Check engine ventilation hoses. Check oil separator.
Engine oil leaks	Reduced throughput/blockage of ventilation system	Check engine ventilation hoses. Check oil separator.

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 more complete troubleshooting chart, refer to Section 303-14, Electronic Engine Management System, in the Service Manual.

DTC	Description	Possible reason	Action
P040100	Insufficient flow registered in the exhaust gas recirculation system A	Exhaust Gas Recirculation (EGR) valve is not installed correctly or is not secured EGR pipe blockage EGR valve stuck closed, blockage EGR heat exchanger blockage EGR valve malfunction MAF sensor malfunction	Refer to the appropriate section in the service manual. Check the EGR valve, coolers and piping. Refer to the electrical manual and check the MAF sensor and circuits. Allow the engine to warm up, turn the ignition off and on. Using the data logger function, check the EGR valve angle. Command the valve actuator to a pulse width modulated control of 0%, then 100% and recheck the reading. The angle should be between 5% and 95%. If not, install a new valve as necessary. Clear the DTCs and verify proper operation.
P040200	Excessive flow rate detected in EGR system A	Exhaust Gas Recirculation (EGR) valve is not installed correctly or is not secured EGR pipe blockage EGR valve sticking EGR heat exchanger blockage EGR Valve Circuit High Resistance EGR valve electrical circuit: short to ground EGR valve electrical circuit: short circuit to battery + EGR valve malfunction MAF sensor malfunction	Refer to the appropriate section in the service manual. Check the EGR valve, coolers and piping. Refer to the electrical manual and check the MAF sensor and circuits. Allow the engine to warm up, turn the ignition off and on. Using the data logger function, check the EGR valve angle. Command the valve actuator to a pulse width modulated control of 0%, then 100% and recheck the reading. The angle should be between 5% and 95%. If not, install a new valve as necessary. Clear the DTCs and verify proper operation.
P040300	Exhaust Gas Recirculation Control Circuit A	High resistance in the exhaust gas recirculation (EGR) valve circuit EGR valve electrical circuit: short to ground EGR valve electrical circuit: short circuit to battery + EGR valve malfunction	Refer to the appropriate section in the service manual. Check the EGR valve, coolers and piping. Refer to the electrical manual and check the MAF sensor and circuits. Allow the engine to warm up, turn the ignition off and on. Using the data logger function, check the EGR valve angle. Command the valve actuator to a pulse width modulated control of 0%, then 100% and recheck the reading. The angle should be between 5% and 95%. If not, install a new valve as necessary. Clear the DTCs and verify proper operation.
P040400	Exhaust Gas Recirculation (EGR) Control Circuit A Range/Performance Problem	Intake Air Temperature (IAT) Sensor Malfunction Manifold Pressure (MAP) Sensor Malfunction MAF sensor malfunction Exhaust Gas Recirculation (EGR) Valve Stuck EGR Valve Circuit High Resistance EGR valve electrical circuit: short to ground EGR valve electrical circuit: short circuit to battery + EGR valve malfunction	Refer to the appropriate section in the service manual. Check the EGR valve, coolers and piping. Refer to the electrical manual and check the MAF sensor and circuits. Allow the engine to warm up, turn the ignition off and on. Using the data logger function, check the EGR valve angle. Command the valve actuator to a pulse width modulated control of 0%, then 100% and recheck the reading. The angle should be between 5% and 95%. If not, install a new valve as necessary. Clear the DTCs and verify proper operation.
P040500	Exhaust Gas Recirculation Sensor A Circuit Low Voltage	High resistance in the exhaust gas recirculation (EGR) valve circuit EGR valve electrical circuit: short to ground EGR valve malfunction	Refer to the appropriate section in the service manual. Check the EGR valve, coolers and piping. Refer to the electrical manual and check the MAF sensor and circuits. Allow the engine to warm up, turn the ignition off and on. Using the data logger function, check the EGR valve angle. Command the valve actuator to a pulse width modulated control of 0%, then 100% and recheck the reading. The angle should be between 5% and 95%. If not, install a new valve as necessary. Clear the DTCs and verify proper operation.
P040600	Exhaust Gas Recirculation Sensor A Circuit High Voltage	Exhaust Gas Recirculation (EGR) Valve Circuit Short to Battery Positive EGR valve malfunction	Refer to the appropriate section in the service manual. Check the EGR valve, coolers and piping. Refer to the electrical manual and check the MAF sensor and circuits. Allow the engine to warm up, turn the ignition off and on. Using the data logger function, check the EGR valve angle. Command the valve actuator to a pulse width modulated control of 0%, then 100% and recheck the reading. The angle should be between 5% and 95%. If not, install a new valve as necessary. Clear the DTCs and verify proper operation.
P040700	Low Voltage in Exhaust Gas Recirculation Sensor B Circuit	Exhaust Gas Recirculation (EGR) Throttle Position Sensor Circuit High Resistance Exhaust Gas Recirculation (EGR) Throttle Position Sensor Circuit Short to Ground EGR modulator failure	Check the EGR throttle position sensor and electrical circuits. Refer to the electrical manual. If no fault is found in the electrical circuits, install a new EGR valve. Clear DTCs and check for proper operation.
P040800	Exhaust Gas Recirculation Sensor B Circuit High Voltage	Exhaust Gas Recirculation (EGR) Throttle Position Sensor Circuit Short to Battery EGR modulator failure	Check the EGR throttle position sensor and electrical circuits. Refer to the electrical manuals. If no fault is found in the electrical circuits, install a new EGR valve. Clear DTCs and check for proper operation.
P048700	Open circuit in the A control circuit of the throttle valve of the exhaust gas recirculation system	Exhaust Gas Recirculation (EGR) Throttle Position Sensor Circuit High Resistance Exhaust Gas Recirculation (EGR) Throttle Position Sensor Circuit Short to Ground Exhaust Gas Recirculation (EGR) Throttle Position Sensor Circuit Short to Battery EGR modulator failure	Check the EGR throttle position sensor and electrical circuits. Refer to the electrical equipment manual. Using the data logging function, check the EGR throttle position when the ignition is on and the engine is off, and record the reading. Issue a command to the actuator for a 100% width modulated control pulse (PWM) and check the position reading. The reading should be in the range of 80-95%. Issue a command to the actuator for a 0% width modulated control pulse (PWM) and check the position reading. The reading should be in the range of 5-20%. Manually close and open the throttle valve and check the resistance. The resistance should be between 300 and 2500 ohms. If the values do not fall within this range, install a new EGR valve. Clear the DTC codes and check that they work correctly. If the problem still persists, ECM is suspected. If an ECM malfunction is suspected, refer to the Warranty Service Policy and Procedures manual.
P048800	Exhaust Gas Recirculation (EGR) Throttle Control A Circuit Range/Performance Problem	Exhaust Gas Recirculation (EGR) Throttle Position Sensor Circuit High Resistance Exhaust Gas Recirculation (EGR) Throttle Position Sensor Circuit Short to Ground Exhaust Gas Recirculation (EGR) Throttle Position Sensor Circuit Short to Battery EGR modulator failure	Check the EGR throttle position sensor and electrical circuits. Refer to the electrical equipment manual. Using the data logging function, check the EGR throttle position when the ignition is on and the engine is off, and record the reading. Issue a command to the actuator for a 100% width modulated control pulse (PWM) and check the position reading. The reading should be in the range of 80-95%. Issue a command to the actuator for a 0% width modulated control pulse (PWM) and check the position reading. The reading should be in the range of 5-20%. Manually close and open the throttle valve and check the resistance. The resistance should be between 300 and 2500 ohms. If the values do not fall within this range, install a new EGR valve. Clear the DTC codes and check that they work correctly. If the problem still persists, ECM is suspected. If an ECM malfunction is suspected, refer to the Warranty Service Policy and Procedures manual.
P133400	Problems with the minimum/maximum limit positions of the EGR throttle position sensor	Exhaust Gas Recirculation (EGR) Valve Stuck EGR Valve Circuit High Resistance EGR valve electrical circuit: short to ground EGR valve electrical circuit: short circuit to battery + Air intake shutoff throttle valve sticking Throttle Air Intake Shutoff Valve Circuit High Resistance Air Intake Throttle Valve Circuit Short to Ground Throttle Air Intake Shutoff Valve Electrical Circuit: Short to Battery + Malfunction of the air intake shut-off throttle valve: ECM failure	Check the EGR valve and electrical circuits. Refer to the electrical manual. Refer to the appropriate section in the workshop manual. If the module is suspected, refer to the warranty policy and procedures manual.
P133500	Problems with the minimum/maximum limit positions of the EGR position sensor	EGR Valve Circuit High Resistance EGR valve electrical circuit: short to ground EGR valve electrical circuit: short circuit to battery + EGR valve malfunction	Check the EGR valve and electrical circuits. Refer to the electrical manuals. Using the data logger function, check the EGR valve angles and command the valve to a 0% pulse width modulated (PWM) control. Check the angle again. The reading should be between 0 and 20%. If the value is outside this range, install a new valve. Refer to the appropriate section in the service manual. Clear the DTCs and verify proper operation.
P140A00	Low Voltage in Exhaust Gas Recirculation Sensor C Circuit	EGR valve electrical circuit (left bank of cylinders): high resistance EGR valve electrical circuit: short to ground EGR valve malfunction	Check the EGR valve and electrical circuits. Refer to the electrical manual. Using the data logger function, check the EGR valve angle with the ignition on and the engine off. Send a 0% and then 100% pulse width modulated control pulse to the valve angle and check the angle values. The angles should be between 0-20% and 80-95%. If not, install a new valve. Refer to the appropriate section in the service manual. Clear the DTCs and check for proper operation.
P140B00	Exhaust Gas Recirculation Sensor C Circuit High Voltage	EGR valve electrical circuit (left bank of cylinders): short circuit to battery + EGR valve malfunction	Check the EGR valve and electrical circuits. Refer to the electrical manual. Using the data logger function, check the EGR valve angle with the ignition on and the engine off. Send a 0% and then 100% pulse width modulated control pulse to the valve angle and check the angle values. The angles should be between 0-20% and 80-95%. If not, install a new valve. Refer to the appropriate section in the service manual. Clear the DTCs and check for proper operation.
P140C00	Electrical circuit B of the exhaust gas recirculation system control	Throttle Air Intake Shutoff Valve Circuit High Resistance Air Intake Throttle Valve Circuit Short to Ground Throttle Air Intake Shutoff Valve Electrical Circuit: Short to Battery + Malfunction of the air intake shut-off throttle valve: ECM failure	Check the EGR valve and electrical circuits. Refer to the electrical manuals. If the module is suspected, refer to the warranty policy and procedures manual.
P140D00	Exhaust Gas Recirculation Control Circuit B Range/Performance Problems	Exhaust Gas Recirculation (EGR) Valve Circuit Range/Performance Problems (left bank of cylinders) Intake Air Temperature (IAT) Sensor Malfunction Manifold Absolute Pressure (MAP) Sensor Malfunction Mass Air Flow (MAF) Sensor Malfunction EGR valve stuck closed, blockage EGR Valve Circuit High Resistance EGR valve electrical circuit: short to ground EGR valve electrical circuit: short circuit to battery + EGR valve malfunction	Check the IAT, MAP, and MAF sensors and electrical circuits. Refer to the electrical manual. The left bank EGR valve circuit tests are described in the appropriate section of the workshop manual.
P140E00	Problems with minimum/maximum limit positions of sensor C of the EGR system	High resistance in the exhaust gas recirculation (EGR) valve circuit (left bank of cylinders) EGR valve electrical circuit: short to ground EGR valve electrical circuit: short circuit to battery + EGR valve malfunction	Check the EGR valve and electrical circuits. Refer to the electrical manuals. Using the data logger function, check the EGR valve angles and command the valve to a 0% pulse width modulated (PWM) control. Check the angle again. The value should be 0 - 20%. If the value is outside this range, install a new valve. Refer to the appropriate section in the service manual. Clear the DTCs and check for proper operation.
P141A00	Intermittent / erratic malfunction in the electrical circuit of the exhaust gas recirculation sensor A	EGR valve electrical circuit (right bank of cylinders): high resistance EGR valve electrical circuit: short to ground EGR valve electrical circuit: short circuit to battery + EGR valve malfunction	Check the EGR valve and electrical circuits. Refer to the electrical manuals. Start the engine and allow it to warm up. Using the data logger function, check the position of the EGR valve. After another 5 seconds, check the position again. If the value has increased by more than 80% in 10 ms, recheck the electrical circuits. If no fault is found in the electrical circuits, install a new EGR valve. Refer to the appropriate section in the workshop manual. Clear the DTCs and check for proper operation.
P141B00	Intermittent / erratic malfunction in the electrical circuit of the sensor In the exhaust gas recirculation system	Throttle Air Intake Shutoff Valve Circuit High Resistance Air Intake Throttle Valve Circuit Short to Ground Throttle Air Intake Shutoff Valve Electrical Circuit: Short to Battery + Malfunction of the air intake shut-off throttle valve:	Check the EGR valve and electrical circuits. Refer to the electrical manuals. Start the engine and allow it to warm up. Using the data logger function, check the position of the EGR valve. After another 5 seconds, check the position again. If the value has increased by more than 80% in 10 ms, recheck the electrical circuits. If no fault is found in the electrical circuits, install a new EGR valve. Refer to the appropriate section in the workshop manual. Clear the DTCs and check for proper operation.
P141C00	Intermittent / erratic malfunction in the electrical circuit of sensor C of the exhaust gas recirculation system	EGR valve electrical circuit (left bank of cylinders): high resistance EGR valve electrical circuit: short to ground EGR valve electrical circuit: short circuit to battery + EGR valve malfunction ECM failure	Check the EGR valve and electrical circuits. Refer to the electrical manuals. Start the engine and allow it to warm up. Using the data logger function, check the position of the EGR valve. After another 5 seconds, check the position again. If the value has increased by more than 80% in 10 ms, recheck the electrical circuits. If no fault is found in the electrical circuits, install a new EGR valve. Refer to the appropriate section in the workshop manual. Clear the DTCs and check for proper operation.
P214100	Exhaust Gas Recirculation Throttle Control Circuit A Low Voltage	Exhaust Gas Recirculation (EGR) Sensor Circuit Short to Ground/Byte/Other Circuits EGR Sensor Circuits: High Resistance EGR sensor malfunction	Check the EGR sensor circuits. Refer to the electrical manuals. Repair as necessary. Clear DTCs and test for proper operation. Using the data logger function, read the difference between the eGr throttle position commanded and actual position and the EGR throttle position. Verify that the throttle valve is open and command the throttle valve closed. Verify that the throttle position value increases above 90%. Verify the difference between the commanded and actual position. This value should not exceed a maximum of 5% or a minimum of -15%. Verify that the EGR throttle valve is not sticking. Install a new right valve if necessary. Refer to the appropriate section in the workshop manual. Clear DTCs and test for proper operation.
P214200	Exhaust Gas Recirculation Throttle Control Circuit A High Voltage	Exhaust Gas Recirculation (EGR) Sensor Circuit Short to Ground/Byte/Other Circuits EGR Sensor Circuits: High Resistance EGR sensor malfunction	Check the EGR sensor circuits. Refer to the electrical manuals. Repair as necessary. Clear DTCs and test for proper operation. Using the data logger function, read the difference between the eGr throttle position commanded and actual position and the actual EGR throttle position. Verify that the throttle valve is open and command the throttle valve closed. Verify that the throttle position value increases above 90%. Verify the difference between the commanded and actual position. This value should not exceed a maximum of 5% or a minimum of -15%. Verify that the EGR throttle valve is not sticking. Install a new left valve if necessary. Refer to the appropriate section in the workshop manual. Clear DTCs and test for proper operation.