1998 AUDI A4 check engine

15-73

Checking activation

Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel Injection & Ignition,
Engine Code(s): APB, Repair Group 01

If LED does not blink or if it remains constantly lit:
Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel Injection & Ignition,
Engine Code(s): APB, Repair Group 24
- Connect VAG 1527B voltage tester between terminal 1 (+) and 2.
- Initiate output Diagnostic Test Mode (DTM) and activate valve for
camshaft adjustment.

LED must blink.
- Connect VAG 1598/31 test box at wiring harness to ECM, do not
connect ECM.
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15-74


Valve 1 for camshaft adjustment -N205- and valve 2 for camshaft
adjustment -N208-
If wire connection is OK:
Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel Injection & Ignition, Engine Code(s): APB, Repair Group 24

If no malfunctions are detected: - Check following wire connections for open circuit and short circuit to
Ground (GND) and B+:
Harness connector
terminal
VAG 1598/31 or test box
Bushing
2 Electrical Wiring Diagrams, Troubleshooting
&Component Locations
- Repair Ground (GND) connection or open circuit if necessary.
- Replace Engine Control Module (ECM).- Replace mechanical camshaft adjuster.
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15-88

Hydraulic lifters, checking


Notes:

Replace malfunctioning lifters completely (lifters
cannot be adjusted or repaired).
When new lifters have been installed the engine
must not be started for about 30 minutes
(otherwise valves will strike pistons).
Irregular valve noises when starting engine are
normal.

- Start engine and run until coolant temperature
reaches approx. 80 C.

- Increase engine speed to about 2500 RPM for
approx. 2 minutes: if necessary, perform road
test.
If the hydraulic lifters are still noisy, locate
malfunctioning lifters as follows:

- Remove cylinder head cover.

- Rotate crankshaft clockwise by turning securing
bolt for toothed belt sprocket until cams of lifters
to be checked are pointing upward.
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15-95

Valve guides, checking

When repairing engines or cylinder heads with
leaking valves, it is not sufficient to reface the
valve seats and replace the valves. The valve
guides must also be checked for wear. This is
particularly important on high-mileage engines.

Wear limit
If the wear limit is exceeded, replace cylinder head. - Insert valve into valve guide so that end of valve stem is flush with end
of guide. The valve stems have different diameters, so only use an inlet
valve in an inlet guide and an exhaust valve in an exhaust guide.
- Measure amount of rock. Inlet valve guide
Exhaust valve guide
0.8 mm 0.8 mm
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