Checking vacuum hoses and vacuum switch for rear differential lock F363 — VW
Checking vacuum hoses and vacuum switch for rear differential lock F363 on VW: factory workshop procedure for engines CAAA, CAAB, CAAC, CAAD.
Workshop procedure for VW — the factory write-up, straight from real workshop data.
📋 Procedure
Checking vacuum hoses and
vacuum switch for rear differential lock
F363
Test procedure
The non-return valve and vacuum hoses leading to
differential lock valve 1
N125
and
differential lock valve 2
N126
must be checked first
Chapter
Remove front left underbody cover
General body repairs, exterior
Rep. gr.
66
Underbody cover; Removing and installing underbody covers
.
Pull vacuum hose
arrow
off from
differential lock valve 1
N125
.
Pull vacuum hose
arrow
off from
differential lock valve 2
N126
.
Connect
hand vacuum pump
VAS 6213
in turn to one of the removed vacuum hoses and generate a vacuum of 0.6 bar.
Observe pressure gauge of
hand vacuum pump
VAS 6213
for approx. 30 seconds.
Vacuum must not drop.
If pressure does not drop:
First pull vacuum hose off at
hand vacuum pump
VAS 6213
.
If there is no leak in vacuum hose, then a hiss is clearly audible when vacuum in vacuum reservoir is released.
Reconnect vacuum hoses.
If vacuum drops:
Pull vacuum hoses
1
and
2
off from
vacuum switch for rear differential lock
F363
3
. Seal openings of vacuum hoses with clean bung from
engine bung set
VAS 6122
.
Connect
hand vacuum pump
VAS 6213
to pulled-off vacuum reservoir and generate a partial vacuum of 0.6 bar.
Observe pressure gauge of
hand vacuum pump
VAS 6213
for approx. 30 seconds.
Vacuum must not drop.
If vacuum drops:
Renew leaking vacuum hose.
If pressure does not drop:
Reconnect vacuum hoses to valves.
Test procedure for
vacuum switch for rear differential lock
F363
Pull vacuum hose
1
off from
vacuum switch for rear differential lock
F363
3
.
Connect
hand vacuum pump
VAS 6213
to connection on
vacuum switch for rear differential lock
F363
and generate a vacuum of 0.6 bar.
Lever
1
must then move towards differential lock
arrow
.
Observe pressure gauge of
hand vacuum pump
VAS 6213
for approx. 30 seconds.
Vacuum must not drop.
If vacuum drops:
Renew
vacuum switch for rear differential lock
F363
Rep. gr.
39
Final drive; Assembly overview - final drive
.
Then pull vacuum hose
2
off from
vacuum switch for rear differential lock
F363
3
.
Connect
hand vacuum pump
VAS 6213
to connection on
vacuum switch for rear differential lock
F363
and generate a vacuum of 0.6 bar.
Observe pressure gauge of
hand vacuum pump
VAS 6213
for approx. 30 seconds.
Vacuum must not drop.
If vacuum drops:
Renew
vacuum switch for rear differential lock
F363
Rep. gr.
39
Final drive; Assembly overview - final drive
.
TorqFix answers live for your specific car — tell it the engine code and it serves the matching sequence, torque figures and wiring for that exact variant.
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Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
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The story behind TorqFix →Workshop data on this page last updated 20 Sep 2026.