In the previous article, we covered the interpretation of fault codes DF001 to DF082 for the Renault Mégane 2 petrol engine.
We continue:
DF083 Downstream oxygen sensor heater circuit
If faults DF046 or DF084 are present or stored, handle them first.
Diagnostic conditions for a stored fault:
The fault is considered present after a 10-second period with the engine running.
Check the cleanliness and condition of the downstream oxygen sensor connector.
With the card inserted in the reader in the 2nd fixed position, check for +12 V at the downstream oxygen sensor connector (see the connector pin number on the relevant wiring diagram).
If +12 V is not present:
- disconnect the battery;
- disconnect the connector marked «PPM1» in the protection and switching unit;
- check the cleanliness and condition of the connector;
- connect the universal test board and check the following circuit for continuity:
Protection and switching unit, connector PPM1 pin 2 → Downstream oxygen sensor.
Reconnect the protection and switching unit connector and reconnect the battery.
If, with the card in the 2nd fixed position, +12 V is still not present at the downstream oxygen sensor connector, this indicates a fault in the protection and switching unit.
Disconnect the battery and the injection ECU.
Check the cleanliness and condition of the connector.
Connect the universal test board. Check the following circuit for continuity and short circuits:
ECU, pin L3, connector C → Downstream oxygen sensor (See the connector pin number on the relevant wiring diagram).
Check the resistance of the downstream oxygen sensor heating element.
If the value is not within specification, replace the downstream oxygen sensor.
If the fault persists, handle other faults, then proceed to conformity check.
After repair:
Perform the «Diagnostic conditions for a stored fault»:
- If the fault is present, continue fault handling.
- If the fault is stored, disregard it.
Handle other possible faults. Clear fault information from memory.
DF084 Actuator control circuit
Disconnect the battery and the injection ECU.
Check the cleanliness and condition of the ECU connections.
Disconnect the «PEM» connector in the protection and switching unit and check the cleanliness and condition of the connections.
Connect the universal test board. Check the following circuit for continuity and short circuits:
ECU pin D4, connector B → Protection and switching unit, connector PEM, pin 2 (See the connector pin number on the relevant wiring diagram).
If the fault persists, this indicates a fault in the protection and switching unit (the actuator relay is integrated in the protection and switching unit and is not replaceable).
DF085 Fuel pump relay control circuit
Causes and consequences: open circuit; short to earth; short to +12 V.
Diagnostic conditions for a stored fault:
The fault is considered present after inserting the card into the reader in the 2nd fixed position.
Disconnect the battery and the injection ECU.
Check the cleanliness and condition of the ECU connections.
Disconnect the «PEM» connector in the protection and switching unit and check the cleanliness and condition of the connections.
Connect the universal test board. Check the following circuit for continuity and short circuits:
ECU, pin D1, connector C → Protection and switching unit, connector PEM pin 1 (See the connector pin number on the relevant wiring diagram).
If the fault persists, this indicates a fault in the protection and switching unit (the fuel pump relay is integrated in the protection and switching unit and is not replaceable).
DF088 Knock sensor circuit
Diagnostic conditions for a stored fault:
The fault is considered present after a road test with the engine hot, at an engine speed above 2500 rpm.
Check the cleanliness and condition of the knock sensor and its connector.
Check the knock sensor tightening torque.
Disconnect the battery and the injection ECU.
Check the cleanliness and condition of the connector.
Connect the universal test board.
Check the following circuits for continuity and short circuits:
- ECU pin B3, connector B → Knock sensor;
- ECU pin B4, connector B → Knock sensor;
- ECU pin B2, connector B → Knock sensor screen (see pin numbers on the relevant wiring diagram).
Check the fuel quality in the tank.
Check the condition of the spark plugs.
If the fault persists, handle other faults, then proceed to conformity check.
DF089 Absolute pressure sensor circuit
Possible cause: voltage out of range or signal inconsistent.
Diagnostic conditions for a stored fault:
The fault is considered present after:
- moving the card to the 1st fixed position with loss of communication;
- inserting the card into the 2nd fixed position and restoring communication;
- a 10-second period with the engine running at idle.
Check the cleanliness and condition of the absolute pressure sensor and its connector.
Disconnect the battery and the injection ECU.
Check the cleanliness and condition of the connector.
Connect the universal test board.
Check the following circuits for continuity and short circuits:
- ECU, pin H2, connector B → Absolute pressure sensor;
- ECU, pin H3, connector B → Absolute pressure sensor;
- ECU, pin H4, connector B → Absolute pressure sensor.
(see pin numbers on the relevant wiring diagram).
If fault DF012 is present or stored, handle this fault.
If the fault persists, handle other faults, then proceed to conformity check.
DF091 Vehicle speed information
Cause and consequences: incorrect vehicle speed signal from the ABS.
Diagnostic conditions for a stored fault:
The fault is considered present with the engine running.
Perform a multiplex network test.
If the fault persists, perform a diagnosis of the ABS and stability control system.
DF092 Upstream oxygen sensor circuit
Cause and consequences: open circuit, short to earth, short to +12 V.
If faults DF046, DF082 or DF084 are present or stored, handle them first.
Diagnostic conditions for a stored fault:
The fault is considered present after a 5-minute delay during fuel mixture regulation (engine running).
Check the cleanliness and condition of the upstream oxygen sensor connector.
Disconnect the battery and the injection ECU.
Check the cleanliness and condition of the connector.
Connect the universal test board. Check the following circuits for continuity and short circuits:
- ECU, pin C1, connector C → Upstream oxygen sensor;
- ECU, pin B1, connector C → Upstream oxygen sensor (see pin numbers on the relevant wiring diagram).
If the fault persists, handle other faults, then proceed to conformity check.
DF093 Downstream oxygen sensor circuit
If faults DF084, DF046 or DF083 are present or stored, handle them first.
Diagnostic conditions for a stored fault:
The fault is considered present in one of the following cases:
- During a smooth driving road test, after the engine cooling fan has started and the dual fuel mixture regulation loop has been activated (ET056 displayed as «ACTIVE»).
- During a smooth driving road test, after the engine cooling fan has operated, immediately followed by a downhill road test with the accelerator pedal released (fuel cut-off during engine braking).
Check the cleanliness and condition of the downstream oxygen sensor connector.
Disconnect the battery and the injection ECU.
Check the cleanliness and condition of the connector.
Connect the universal test board. Check the following circuits for continuity and short circuits:
- ECU, pin A2, connector C → Downstream oxygen sensor;
- ECU, pin B2, connector C → Downstream oxygen sensor (see pin numbers on the relevant wiring diagram).
If the fault persists, handle other faults, then proceed to conformity check.
DF095 Throttle position sensor track 1 circuit
Causes and consequences: open circuit or short to earth, short to +12 V, inconsistency between track 1 and track 2 signals of the throttle position sensor.
Diagnostic conditions for a stored fault:
The fault is considered present after a change in engine speed.
IMPORTANT NOTE: Do not operate the vehicle under any circumstances without first ensuring that there are no faults related to the throttle body.
Check the cleanliness of the throttle body and ensure the throttle plate moves freely (no sticking).
Check the cleanliness and condition of the throttle body connector.
Disconnect the battery and the injection ECU.
Check the cleanliness and condition of the connector.
Connect the universal test board. Check the following circuits for continuity and short circuits:
- ECU, pin G4, connector B → Throttle position sensor, track 1;
- ECU, pin G3, connector B → Throttle position sensor, track 1;
- ECU, pin G2, connector B → Throttle position sensor, track 1.
(see pin numbers on the relevant wiring diagram).
If fault DF011 is present or stored, handle this fault.
If the fault persists, handle other faults, then proceed to conformity check.
DF096 Throttle position sensor track 2 circuit
Cause and consequences: short to earth, open circuit or short to +12 V.
Diagnostic conditions for a stored fault:
The fault is considered present after a change in engine speed.
IMPORTANT NOTE: Do not operate the vehicle under any circumstances without first ensuring that there are no faults related to the throttle body.
Check the cleanliness of the throttle body and ensure the throttle plate moves freely (no sticking).
Check the cleanliness and condition of the throttle body connector.
Disconnect the battery and the injection ECU.
Check the cleanliness and condition of the connector.
Connect the universal test board. Check the following circuits for continuity and short circuits:
- ECU, pin D3, connector B → Throttle position sensor, track 2;
- ECU, pin G2, connector B → Throttle position sensor, track 2;
- ECU, pin G4, connector B → Throttle position sensor, track 2 (see pin numbers on the relevant wiring diagram).
If fault DF011 is present or stored, handle this fault.
If the fault persists, handle other faults, then proceed to conformity check.
DF097 Camshaft position sensor circuit
Causes and consequences: missing tooth on the camshaft sprocket, offset measurement out of range.
If faults DF084 or DF046 are present or stored, handle them first.
Diagnostic conditions for a stored fault:
The fault is considered present after a road test.
Check the cleanliness and condition of the camshaft position sensor connector.
With the card in the 2nd fixed position, check for +12 V at the camshaft position sensor connector (see the connector pin number on the relevant wiring diagram).
If +12 V is not present:
- disconnect the battery;
- disconnect the connector marked «PPM1» in the protection and switching unit;
- check the cleanliness and condition of the connector;
- connect the universal test board and check the following circuit for continuity:
Protection and switching unit, connector PPM1 pin 2 → Camshaft position sensor.
Reconnect the protection and switching unit connector and reconnect the battery.
If, with the card in the 2nd fixed position, +12 V is still not present at the camshaft position sensor connector, this indicates a fault in the protection and switching unit.
Disconnect the battery.
Disconnect the ECU from the vehicle network. Check the cleanliness and condition of the connector.
Connect the universal test board. Check the following circuits for continuity and short circuits:
- ECU, pin E2, connector C → Camshaft position sensor;
- ECU, pin F1, connector C → Camshaft position sensor (see pin numbers on the relevant wiring diagram).
If the fault is not resolved, this is most likely due to a fault with the camshaft position sensor trigger wheel.
DF099 AT ECU or AMT ECU communication via multiplex network
Cause: fault in the connection circuit to the multiplex network.
Diagnostic conditions for a stored fault:
The fault is considered present with the engine running.
Perform a multiplex network test.
If the fault persists, perform a diagnosis of the «Automatic transmission» system.
DF100 Multiplex communication (with the instrument panel)
Cause: fault in the connection circuit to the multiplex network.
Perform a multiplex network test.
If the fault persists, perform a diagnosis of the «Instrument panel».
After repair:
Handle other possible faults. Clear fault information from memory.
DF101 Multiplex communication with the stability control system
Cause: fault in the connection circuit to the multiplex network.
Perform a multiplex network test.
If the fault persists, perform a diagnosis of the ABS and Stability control system.
DF105 Speed regulator/limiter activation circuit
Cause: inconsistency in the position of the speed regulator/limiter switch.
Diagnostic conditions for a stored fault:
The fault is considered present after a road test using first the regulator, then the limiter.
Check the cleanliness and condition of the speed regulator/limiter switch and its connections.
With the card in the 2nd fixed position, check for +12 V at the speed regulator/limiter switch connector (see the connector pin number on the relevant wiring diagram).
Disconnect the battery.
Disconnect the ECU from the vehicle network. Check the cleanliness and condition of the connector.
Connect the universal test board. Check the following circuits for continuity and short circuits:
- ECU, pin A2, connector A → Speed regulator/limiter switch;
- ECU, pin C3, connector A → Speed regulator/limiter switch (see pin numbers on the relevant wiring diagram).
If the fault persists, handle other faults, then proceed to conformity check.
DF106 Speed regulator/limiter switches on the steering wheel
Cause: data inconsistency.
Diagnostic conditions for a stored fault:
The fault is considered present after a road test using first the regulator, then the limiter.
WARNING! To remove or check the speed regulator/limiter switches, the airbag must be removed.
Check the cleanliness and condition of the speed adjustment switches on the steering wheel and their connectors.
Check for an «earth» connection at the speed adjustment switch connectors on the steering wheel (see pin numbers on the relevant wiring diagram).
Disconnect the battery.
Disconnect the ECU from the vehicle network. Check the cleanliness and condition of the connector.
Connect the universal test board. Check the following circuits for continuity and short circuits:
ECU, pin D2, connector A → Steering wheel switch;
ECU, pin D3, connector A → Steering wheel switch (see pin numbers on the relevant wiring diagram).
If the fault persists, handle other faults, then proceed to conformity check.
DF109 Misfires at minimum fuel level
Misfires due to low fuel level.
Causes and consequences: misfires at low fuel level that could damage the catalytic converter.
If the following faults are present or stored, handle them first:
– Fuel supply system: DF085, DF026, DF027, DF028 and DF029.
Diagnostic conditions for a stored fault:
The fault is considered present after engine start.
Check that there is fuel in the tank.
Check the fuel quality.
If a present or stored fault related to misfires exists (DF059, 060, 061, 062, 065, 1.DEF or 2.DEF), handle that fault; fault DF109 can be ignored.
Diagnostic conditions for a stored fault:
The fault is considered present under the following conditions:
- Ensure there are no electrical faults.
- Programming must have been performed.
- The engine must be warm (at least 75 °C).
- With the engine at idle, switch on all electrical consumers for 15 minutes.
If no present or stored misfire-related faults are detected, the misfires were caused by low fuel level.
Clear fault DF109 from memory.
After repair:
Ensure all faults have been resolved.
Do not clear programming data.
To confirm the repair results:
- Repair electrical circuit faults.
- Register the programmable parameters.
- Warm up the engine (at least 75 °C).
- With the engine at idle, switch on all electrical consumers for 15 minutes.
If the fault reappears, continue diagnosis.
DF110 Catalytic converter
Cause: HC emission threshold exceeded as permitted by the on-board diagnostic system.
If other faults are present, handle them first.
There should be no other present or stored faults in the fuel injection system.
After eliminating the causes of misfires, replace the catalytic converter.
After repair:
Handle other possible faults. Clear fault information from memory.
DF125 Torque measurement programming
Cause: programming not performed.
For information: the torque measurement system analyses the crankshaft speed.
Diagnostic conditions for a stored fault:
The fault is considered present after 10 seconds of starter motor operation or when the engine speed exceeds 600 rpm.
Reinitialisation of programming:
Execute command RZ008.
Torque measurement programming:
Engage 3rd gear and increase the engine speed to 4000 rpm, then reduce the speed until fuel injection resumes*.
Repeat the operation twice consecutively.
In rare cases, fault DF125 may appear. (This is the moment when, during deceleration with the accelerator pedal released, the engine speed drops to idle and the engine is back under load).
After repair:
Perform the «Diagnostic conditions for a stored fault»:
- If the fault is present, continue fault handling.
- If the fault is stored, disregard it.
Handle other possible faults. Clear fault information from memory.
DF126 Cabin heating element
Cause: information from the UCH is inconsistent or missing.
Perform a multiplex network test.
If the fault persists, perform a diagnosis of the «Central electronic switching unit in the cabin».
After repair:
Handle other possible faults. Clear fault information from memory.
DF127 Stop lamp switch
Cause: fault in one of the two contacts of the stop lamp switch.
Diagnostic conditions for a stored fault:
The fault is considered present with the engine running, the brake pedal pressed, and the speed regulator switch set to «ON».
Check the condition of the pedal assembly.
Check the cleanliness and condition of the two-contact stop lamp switch and its connector.
Disconnect the battery.
Disconnect the ECU from the vehicle network. Check the cleanliness and condition of the connector.
Connect the universal test board in place of the ECU and check the following circuit for continuity and short circuits:
ECU, pin E4, connector A → Stop lamp switch (see pin numbers on the relevant wiring diagram).
If the fault persists, replace the switch.
After repair:
Handle other possible faults. Clear fault information from memory.
DF128 Stop lamp switch circuit 2
The cause is a fault in both contacts of the stop lamp switch.
If fault DF127 is present, handle it first.
Diagnostic conditions for a stored fault:
The fault is considered present with the engine running, the brake pedal pressed, the speed regulator switch set to «ON», and a set speed activated.
Perform a multiplex network test.
If the fault persists, perform a diagnosis of the «Central electronic switching unit in the cabin».
After repair:
Handle other possible faults. Clear fault information from memory.
