Volkswagen Golf / Golf GTI / Golf Variant. Manual — part 86
the vehicle (often underneath the rear bumper). A passenger-car
exhaust system consists of the following; exhaust manifold, ex‐
haust treatment components, sound absorption components and
the system of pipes connecting these components.
Exhaust Manifold
The manifold is an important component in the exhaust system.
It routes the exhaust gas out of the cylinder outlet ports into the
subsequent exhaust system. The geometry of the manifold (i.e.
length and cross-section of the individual pipes) has an impact on
the performance characteristics, the acoustic behavior of the ex‐
haust system, and the exhaust temperature. In some cases, the
manifold is insulated with an air gap to quickly reach high exhaust
temperature and to shorten the time taken by the catalytic con‐
verter to reach its operating temperature.
Emission Control
The primary emission control component is the catalytic convert‐
er, which breaks down the gaseous pollutants in the exhaust gas
(CO, HC and NOx). Catalytic converters are installed as close as
possible to the engine so that they can quickly reach their oper‐
ating temperature and therefore be effective in urban driving. It
also bears a sound-absorbing function, especially to the higher
frequency portion of the engine combustion noise.
Sound Absorption
Mufflers dampen or absorb the noise produced by engine com‐
bustion. In principle, they can be installed at any position in the
exhaust system. However, they are mostly located in the middle
and rear sections of the exhaust system. Depending on the num‐
ber of cylinders and engine output, generally 1 to 3 mufflers are
used in an exhaust system. In V-engines, the left and right cylin‐
der banks are often run separately, each being fitted with its own
catalytic converters and mufflers. Although the aim of mufflers is
to reduce noise in compliance with legislations, they can also help
to create the sound specific to the type of vehicle.
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2. Description and Operation
17
3
Diagnosis and Testing
♦
⇒ “3.1 Preliminary Check ”, page 18
♦
⇒ “3.2 Readiness Codes”, page 19
♦
⇒ “3.3 Diagnostic Modes 01 - 0A”, page 21
♦
⇒ “3.4 Engine DTC Tables”, page 46
♦
⇒ “3.5 Transmission DTC Tables”, page 396
♦
⇒ “3.6 Diagnostic Procedures”, page 456
3.1
Preliminary Check
Note
♦
Before performing any pin point test or component diagnosis,
a Preliminary Check must be performed.
♦
Check for Technical Bulletins that may supersede any infor‐
mation included in the repair manual or GST Manual.
♦ For Electrical Testing: Refer to
♦ For Fuel System Mechanical Testing: Refer to
.
Electrical Testing
Step
Procedure
Result / Action to Take
1
• CONNECT: Scan Tool.
• IGNITION: ON.
• CHECK: For stored or related DTCs.
– Were any other DTCs stored?
– YES:
♦ GO TO: Step 2
– NO:
♦ GO TO: Step 3
2
• Repair these DTCs first before performing any
of the following steps.
♦ GO TO: Proper Diagnostic procedure per the
stored DTC. Refer to
⇒ “3.4 Engine DTC Tables”, page 46
3
• Using the Scan Tool, erase the DTC memory.
Refer to
⇒ “3.3.4 Diagnostic Mode 04 - Erase DTC
• Perform a road test to attempt to duplicate the
customers complaint.
– Does DTC return?
– YES:
♦ GO TO: Step 4
– NO:
♦ GO TO: Step 5
4
• Perform the diagnostic procedure for that DTC. ♦ GO TO: Proper Diagnostic procedure per the
stored DTC. Refer to
⇒ “3.4 Engine DTC Tables”, page 46
5
• FAULT: Intermittent or a sporadic condition.
• CHECK: Suspected components.
• PERFORM: Visual Inspection of wiring and
components.
• CHECK: Wiring for open, high resistance,
short or harness connector for damage, corro‐
sion, loose or broken terminals.
• REPAIR: Faulty wiring or connector.
♦ Perform a road test to verify the repair.
♦ Generate readiness code. Refer to
⇒ “3.2 Readiness Codes”, page 19
.
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Fuel System Mechanical Testing
Check the following items for possible mechanical delivery defi‐
ciency:
• Fuel level in tank is too low.
• Fuel lines pinched.
• Fuel filter plugged.
• Fuel pump delivery unit internal leak.
• Clogged injectors.
• Poor fuel quantity delivery. Refer to appropriate repair manual.
3.2
Readiness Codes
Caution
When performing the Readiness drive cycle operation, pay
strict attention to driving conditions and observe and obey all
posted speed limits.
Readiness code description
Diagnostics are performed at regular intervals during normal ve‐
hicle operation. After repairing an emissions related system, a
readiness code is generated by road testing the vehicle.
If a malfunction is recognized during the drive cycle, it will be
stored in the DTC memory.
The OBD drive cycle operation will be monitored with a hand held
diagnostic tool. Consult the manufacturer's instruction manual for
correct tool operation.
The readiness code is erased every time the DTC memory is
erased or any time the battery is disconnected. If the DTC mem‐
ory has been erased or the battery is disconnected, a new read‐
iness code must be generated.
Only erase the DTC memory if a DTC has been stored.
General recommendations
Most monitors will complete easier and quicker using a “steady-
foot” and “smooth” acceleration during the drive cycle operation.
Operating conditions
For the EVAP monitor test, the coolant temperature and the am‐
bient air temperature must be between 10° C and 35° C with a
difference between them no greater than 4° C. The ambient air
temperature must not change more than 4° C during the drive
cycle procedure (e.g. when driving out of a heated workshop in
the winter).
Note
Do not assume that the scan tool ID and engine code are correct
if the scan tool communicates. The scan tool does not use the ID
to establish communication—the units are automatically identi‐
fied.
Test requirements
• NO DTC in memory
• Switch OFF all electrical and electronic accessories
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3. Diagnosis and Testing
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• Necessary driving speed: 50 – 70 mph
• Drive profile takes approx. 60 – 90 min.
Readiness Drive Cycle Procedure
– CONNECT: Scan Tool
Step
Procedure
Result / Action to Take
1
Activate Monitors:
• START: Engine and idle for 2 – 3 min.
♦ Monitoring Active.
♦ Executes Misfire Monitoring.
2
O2 Sensor Monitoring:
• DRIVE: Vehicle at 45 – 55 mph for a continu‐
ous 7 minute period. Avoid stopping.
♦ Executes O2 Sensor Monitoring.
♦ Executes Fuel Trim Monitoring.
♦ Executes EVAP Monitoring.
3
Fuel Cut-Off Monitoring:
• ACCELERATE: Vehicle to an engine speed of
5,000 RPM; lift off the throttle until the engine
speed is around 1,200 RPM.
♦ Fuel Cut-Off Monitoring Ready.
4
Catalyst Monitoring:
• ACCELERATE: Vehicle smoothly to 60 – 65
mph, cruise at a constant speed for 5 min.
♦ Executes Catalyst Monitoring.
♦ Executes O2 Sensor Monitoring.
♦ Executes Fuel Trim Monitoring.
♦ Executes Misfire Monitoring.
♦ Executes EVAP Monitoring.
5
Secondary Air Injection, EVAP Monitoring:
• DRIVE: Vehicle for 30 – 40 min. at a constant
speed of 50 – 70 mph in high gear for 2 min
with no coasting.
♦ Executes Secondary Air Injection Monitoring.
♦ Executes EVAP Monitoring.
• Check the status of the readiness code.
– If any engine monitor fails the drive cycle test. Repeat the drive
cycle test until all engine monitors have successfully run
through and passed.
Note
♦
When repeating the drive cycle operation for a failed evapo‐
rative or thermostat monitor, allow the engine to cool until the
coolant temperature and the ambient air temperature are be
between 10° C and 35° C with a difference no greater than 4°
C and repeat the drive cycle operation.
♦
Depending on the scan tool used. The readiness code status
may be displayed as complete, passed or OK. At an exterior
temperature < 7° C, the setting of the readiness for the NOx
catalytic converter test is delayed. Here the vehicle must be
Driven considerably longer.
Readiness Codes and Monitoring Completed
1 - If any engine monitor fails the drive cycle test. Repeat the
drive cycle test until all engine monitors have successfully
run through and passed.
2 - If the drive cycle operation fails again.
3 - Check the DTC memory for stored DTCs.
4 - Repair the vehicle if necessary.
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Generic Scan Tool - Edition 04.2015
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Rep. Gr. ST - Generic Scan Tool
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