Page 147 of 198
13B-147V4 MR-372-J84-13B000$120.mif
13B
DDCR INJECTION
Vdiag No.: 44, 48
*Technical Note 3419: Fault finding on the turbocharger for petrol and diesel engines
NOTESOnly consult these tests when dealing with a fault finding chart (ALP) or when
interpreting faults.
Low pressure circuit check TEST 1
Electrical circuit checkTEST 2
Injector checkTEST 3
Inlet circuit checkTEST 5
High pressure system check TEST 6
High pressure circuit sealing check TEST 7
Injector return flowTEST 8
Diesel filter checkTEST 9
Turbocharger solenoid valve checkTEST 10: Apply
TEST 4 of
Technical Note
3419*
Turbocharger air chainTEST 11
TurbochargerTEST 12: Apply
TEST 7 of
Technical Note
3419*
Diesel fuel conformity check TEST 13
DIESEL INJECTION
Fault finding – Tests
Page 149 of 198
13B-149V4 MR-372-J84-13B000$120.mif
DIESEL INJECTION
Fault finding – Tests13B
DDCR INJECTION
Vdiag No.: 44, 48
TEST 2 Electrical circuit check
Check the battery charge and that the alternator is
operating correctly (see 87G, Engine compartment
connection unit for Mégane II or Scénic II).
Is the charging circuit in good order? Carry out the necessary repairs
Check the fuses.
Are the fuses correct? Carry out the necessary repairs
Check that the injection locking relay is operating
correctly.
Is the injection locking relay working properly? Carry out the necessary repairs
Check the engine earths.
Are the engine earths correct?Carry out the necessary repairs
The electrical circuit is in good order.
NO
YES
NO
YES
NO
YES
NO
YES
DDCR_V44_TEST02/DDCR_V48_TEST02
Page 154 of 198
13B-154V4 MR-372-J84-13B000$120.mif
DIESEL INJECTION
Fault finding – Tests13B
DDCR INJECTION
Vdiag No.: 44, 48
The command AC029 High pressure circuit sealing test can locate a leak in the high pressure circuit if a union is
incorrectly fitted or screwed on. This command does not identify a union not tightened to torque.
This command can be used only if the engine temperature is greater than 60ºC.
Watch out for any objects (tool or others) on the sides of the engine housing during the 4 accelerations
(possible vibrations).
Run command AC029, the engine will automatically carry out a cycle of four accelerations to increase the rail
pressure. Check if there are leaks on the high pressure circuit.
TEST 7 High pressure circuit sealing check
NOTESSpecial note:
Certain faults make it impossible to carry out this test - deal with these first.
DDCR_V44_TEST07/DDCR_V48_TEST07
Page 155 of 198

13B-155V4 MR-372-J84-13B000$120.mif
DIESEL INJECTION
Fault finding – Tests13B
DDCR INJECTION
Vdiag No.: 44, 48
TEST 8 Injector return flow
NOTESSpecial note:
Certain faults make it impossible to carry out this test - deal with these first.
Does the engine start?
Command AC029 also checks the return volume of each injector to detect an internal injector leak.
Be careful with any objects (tool or other) on the engine housing during the four cycles of the operation
(possible vibrations).
Tooling required
–Mot. 1711 Injector flow measuring kit.
Or: Use four pipes with internal diameter 4mm and approximately 50 cm in length, and four graduated measuring
cylinders.
Procedure
– Ensure that the engine coolant temperature is above 60°C,
– switch off the ignition,
– disconnect the return pipes from the four injectors,
– cap the pump venturi tube to prevent the low-pressure circuit from depriming,
– connect the four transparent tubes in place of the return pipes,
– put the other ends of the four pipes into four graduated measuring cylinders.
– After finishing these preparations, start the engine and let it idle for 2 minutes.
Note: This idle time must be respected for the test results to be interpreted correctly.
–Run command AC029 High pressure circuit sealing check
.The engine will automatically carry out a cycle of four accelerations to increase the rail pressure and measure the
internal injector leaks under these conditions.
–Once the cycle is complete, run command AC029 again to obtain a correct reading of the return volume of
each injector.
– Switch off the engine at the end of the cycle.
NOA
YES
DDCR_V44_TEST08/DDCR_V48_TEST08
Page 157 of 198

13B-157V4 MR-372-J84-13B000$120.mif
DIESEL INJECTION
Fault finding – Tests13B
DDCR INJECTION
Vdiag No.: 44, 48
TEST 8
CONTINUED 2
If the engine does not start, only the static leak can be measured, that is the leak with the injector closed, not being
actuated and under high pressure.
Make sure that the ignition circuit is working correctly (minimum engine speed 200 rpm).
Tooling required
– Mot. 1711 Injector flow measuring kit.
Or: Use four tubes of internal diameter 4 mm and approximately 50 cm long and a test adapter (TEST IMV).
Procedure
– Switch off the ignition,
– disconnect the return pipes from the four injectors,
– cap the pump venturi tube to prevent the low-pressure circuit from depriming,
– connect the four transparent pipes in place of the return pipes (Mot. 1711),
– disconnect the low pressure actuator from the pump (brown IMV connector) and connect a test IMV or the
adapter of Mot. 1711,
– electrically disconnect the four injectors,
– switch on the ignition and engage the starter for 5 seconds,
– measure the amount of diesel fuel in each pipe.
Replace the injectors that have a leak return greater than 10 cm.
Switch off the ignition, and reconnect the four injectors electrically.
Disconnect the test IMV and reconnect the low-pressure actuator connector to the pump. Disconnect the
four transparent tubes and reconnect the injectors return circuit. Switch on the ignition again, and clear the injection
faults using the diagnostic tool.
A
NO
Page 161 of 198

13B-161V4 MR-372-J84-13B000$120.mif
DIESEL INJECTION
Fault finding – Tests13B
DDCR INJECTION
Vdiag No.: 44, 48
TEST 11
CONTINUED
High pressure circuit check
Note:
Depending on the vehicle type, the best visual access will be
either from above or from below.
Visually inspect the condition of the following components:
– the compressor outlet pipe to the turbocharging air cooler (the
turbocharging air cooler does not exist for all engines),
– outlet pipe of the turbocharging air cooler to the inlet manifold,
– inlet manifold,
– temperature and pressure sensors.
Is one of these components incorrect (disconnected, cut,
bent, pierced or kinked pipes)?Replace the defective parts (see
MR 364 (Mégane II) or 370 (Scénic
II), Mechanical, 12B,
Turbocharging).
Exhaust system check
Visually inspect the condition of the following engine sections:
– from the exhaust manifold circuit to the turbocharger turbine,
– from the turbine outlet pipe to the end of the exhaust pipe,
– from the inlet manifold to the EGR valve
– check that the temperature and pressure sensors are
connected.
Do some of these components have black or white marks on
them? Replace the defective parts (see
MR 364 (Mégane II) or 370 (Scénic
II), Mechanical, 12B,
Turbocharging).
Run TEST 10: Turbocharger control solenoid valve check.
A
NO
YES
NO
YES
NO
Page 165 of 198
13B-165V4 MR-372-J84-13B000$130.mif
13B
DDCR INJECTION
Vdiag No.: 44, 48
NOTESSpecial note:
Only consult this customer complaint after a complete check with the diagnostic
tool.
No dialogue with the computer ALP1
Starting fault:
The engine will not startALP2
The engine starts with difficulty, or starts then stalls ALP3
Starting difficult with warm engine ALP4
Rough idle (pumping)ALP5
Idling speed too high or too low ALP6
Behaviour while driving:
Erratic acceleration/deceleration and engine racing ALP7
Acceleration gapALP8
Engine cut-out (stalling)ALP9
Engine buckingALP10
Loss of powerALP11
Too much powerALP12
Excessive consumptionALP13
Overspeed when releasing accelerator or changing gear ALP14
Engine dies on pulling awayALP15
Noise, odours or smoke:
Engine rattling, noisy engine, turbocharger noise ALP16
Blue, white or black smokeALP17
Oil leaks from the turbocharger ALP18
DIESEL INJECTION
Fault finding – Customer complaints
Page 166 of 198

13B-166
AFTER REPAIRCarry out a road test, then check with the diagnostic tool.
V4 MR-372-J84-13B000$140.mif
13B
InjectionDDCR
Vdiag No.: 44, 48
ALP1 No dialogue with the computer
NOTESOnly consult this customer complaint after a complete check with the diagnostic tool.
To check that the diagnostic tool is not causing the fault, try to establish dialogue with a computer on another
vehicle. If the diagnostic tool is not the cause and communication cannot be established with any other computer
on the same vehicle, it is possible that another computer is disrupting the multiplex network. Check the battery
voltage and make the necessary adjustments to obtain a correct voltage (9.5 V < Battery voltage < 17.5 V).
Carry out fault finding on the multiplex network using the diagnostic tool (see 88B, Multiplexing).
Check the presence and the condition of the injection fuses on the UPC and on the engine fuse box.
Check the connection of the computer connectors and the condition of its connections.
Check the injection computer earths (quality, oxidation, tightness of earth bolts on the battery terminal).
Check that the supply to the computer is correct:
–AP15 between components 1337 and 120,
–NH between earth and component 120,
–3FB1 between components 1337 and 120,
–3FB2 between components 1337 and 120.
Ensure that the supply to the diagnostic socket is correct:
–BP32 between components 225 and 260,
–AP43 between components 225 and 1337,
–MN between earth and component 225,
If dialogue has still not been established after these checks, contact the techline.
DDCR_V44_ALP01/DDCR_V48_ALP01
DIESEL INJECTION
Fault finding – Fault finding charts