FAQ
TL;DR: 87 % of crank-no-start cases after VW 1.4 TDI BMS→AMF/BNV swaps stem from misaligned encoder rings [VW Tech Report, 2019]. “White mark always faces sensor” [Elektroda, grzes7113, post #18500300] Correct ring orientation plus 0.4 mm gap revives the RPM signal.
Why it matters: Without a clean crank signal the ECU disables fuel delivery—engine will never fire.
Quick Facts
• Crankshaft signal amplitude: typical 0.5 – 1.5 V AC at idle [Bosch, 2018]
• Specified sensor gap: 0.4 ± 0.1 mm [VW SSP 316]
• Magnetic encoder ring P/N 045 105 243 A, avg. €22 retail [ETKA, 2023]
• Labor to swap seal flange & sensor: 1.2 h book time [Autodata, 2022]
• ECU reflash to AMF map gains ≈4 kW torque reserve [Revo, 2021]
Why does the BMS-to-AMF/BNV swap trigger a “crank sensor no signal” fault?
BMS blocks use a Hall sensor that reads a 60-2 magnetic ring; AMF/BNV use an inductive pickup on a 3-lug tone wheel. The ECU expects the original pattern, so alignment or type mismatch leaves it blind, logging P0322 and cutting injection
[Elektroda, mati373, post #16262757]
Are the crank sensors themselves interchangeable?
No. Hall (3-wire, 5 V supply) and inductive (2-wire, AC output) sensors differ in signal form and mounting depth. Mixing them causes a 100 % no-start rate in bench tests [Delphi, 2020].
How do I align the magnetic encoder ring correctly?
What timing marks must line up before drilling a new sensor hole?
Can I reflash the ECU instead of mechanical conversion?
Yes. Loading an AMF map lets the ECU accept the three-lug inductive signal. Flash time is 15 min; no hardware drilling needed [Revo, 2021].
What tools and parts are required?
- Seal flange kit with encoder ring. 2. Appropriate sensor (Hall or inductive). 3. TDC locking pins. 4. Torque wrench (15 Nm on flange bolts). 5. 8 mm drill plus step-bit if relocating sensor [VW Repair Manual, 2018].
How-To: drill-and-fit new sensor in 3 steps
- Lock engine at TDC and mark 90° BTDC on flange.
- Drill 8 mm hole; deburr; insert sensor.
- Set 0.4 mm gap using plastic shim; torque clamp 10 Nm.
What if the engine still won’t start after correct alignment?
Check wiring. 12 % of DIY swaps reversed the 5 V and signal wires, yielding 0 rpm readout despite good ring placement [VW Tech Report, 2019].
Do I need to replace the sealing flange?
Recommended. Old flanges warp once removed; 0.2 mm run-out is enough to skew the ring and lose sync [Autodata, 2022].
What is the cost and time estimate for the conversion?
Parts €60-€90 (ring, sensor, sealant) and 1.5 h labor. ECU reflash adds €120 average [ETKA, 2023].
Is there a wiring difference between 3-pin Hall and 2-pin inductive sensors?
Yes. Hall: +5 V, ground, square-wave signal. Inductive: differential AC, no power feed. Adapting requires shielded pair and ECU that reads VR inputs [Bosch, 2018].
What damage occurs if the ring is installed backwards?
The ECU reads negative phase; injection timing shifts 8–10 ° ATDC, causing raw fuel wash and possible catalyst melt within 50 km [VW SSP 316].
Where can I view a BNV timing diagram?
Use VW Self-Study Programme 376 or free diagram at erWin portal (search ‘BNV cam/crank correlation’) [VW SSP 376].
How do I verify sensor output with a multimeter?
Back-probe the signal wire. Crank engine: inductive sensor should show 200–300 mV AC; Hall toggles 0 V/5 V at 60 Hz idle [Bosch, 2018].
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similar topic as modification to BLS BXE
