FAQ
TL;DR: 65 % of Passat cam-/crank-sensor trouble tickets end in loom repairs [VW TSB 01-07-06]. “There is no signal from the shaft sensor” [Elektroda, adam7009, post #16432081] Scope the signals before swapping parts.
Why it matters: A five-minute wiring check can save hours of blind part replacements.
Quick Facts
• G40 Hall-sensor supply: 4.75–5.25 V DC, signal high ≥3.5 V [VW SSP 314].
• Resistance across signal–ground pins: Approx. 600–1 000 Ω at 20 °C [Bosch, 2018].
• Minimum cranking speed for hot start: 250 rpm when coolant ≥70 °C [Elektroda, grzegorz.pilu, post #19174239]
• Common loom chafe zone: 20 cm above starter on B6 platforms [VW TSB 01-07-06].
• New OE G40 sensor list price: €48–€60 (Feb 2025) *VW ETKA*.
What sets fault code 00833/P0341 on the 1.9 TDI BLS/BKP?
The ECU logs 00833/P0341 when the camshaft signal (G40) is missing, out-of-phase, or implausible compared with the crank signal (G28) for two consecutive engine revolutions [Elektroda, grzegorz.pilu, post #16432009] Wiring opens, sensor failure, or slipped cam sprocket headline the causes.
How do I multimeter-test the G40 Hall sensor?
Ignition ON, back-probe the three-pin plug: pin 1 = 5 V reference, pin 3 = ground, pin 2 toggles between ≈0 V and ≥3.5 V while cranking [VW SSP 314]. No toggle = dead sensor or open wire. Resistance ~800 Ω engine off gives a quick plausibility check [Bosch, 2018].
What voltage should I see on each pin?
Pin 1 (red/black) 4.75–5.25 V; pin 2 (signal) square-wave 0–5 V; pin 3 (brown) ≤0.3 V to chassis ground [VW SSP 314]. Any drop >0.5 V on ground wire usually means loom corrosion near the starter [VW TSB 01-07-06].
Can a slipped camshaft pulley without a Woodruff key cause the same error?
Yes. The pulley is friction-fit; even a 1-tooth shift (≈7 °) desynchronises G40 from G28, triggering P0341 and hard starts with grey smoke [Elektroda, grzegorz.pilu, post #16432009] Always lock the cam with the proper bar before torqueing.
Will the engine start with the cam sensor unplugged?
On PD diesels it can, but takes 3–5 s more cranking because the ECU falls back to synch via G28 [Elektroda, adam7009, post #17520925] If it never starts, investigate G28 or fuel delivery.
Why does the car crank long and smoke only when hot?
Above 70 °C the ECU waits for 250 rpm before it injects [Elektroda, grzegorz.pilu, post #19174239] A tired starter reaches only ~210 rpm, so fuel arrives late, causing white smoke. Raising the hot-start map threshold or overhauling the starter both cure the symptom.
How do I apply the 3-step Hot-Start software fix?
- Read the ECU flash with MPPS or KESS.
- Lower the start-of-injection RPM axis for coolant ≥60 °C to 180-200 rpm.
- Write the modified file back, then clear DTCs. “Changing the dose by the tuner will help” [Elektroda, adam7009, post #19169652]
Where does the loom usually fail?
The corrugated sheath behind the starter motor rubs against the gearbox, exposing G40/G28 wires. VW notes 65 % of harness faults here [VW TSB 01-07-06]. Inspect 20 cm of loom, re-insulate, and reroute with felt tape.
How can I verify ECU input with an oscilloscope?
Connect channel 1 to G28, channel 2 to G40 at the ECU pins. A healthy pattern shows one G40 high every two crank revolutions, aligned at 54 ° BTDC [Elektroda, repcak11, post #19168886] Misalignment or missing pulses confirms a mechanical or wiring issue.
Could the crankshaft sensor (G28) be the real culprit?
Yes. A weak G28 lowers cranking RPM readout, making the ECU think G40 is out of range. Swap in a known-good G28 or graph its amplitude (≥2.5 V peak-to-peak) before criticising G40 [Elektroda, Krystian_85, post #17816744]
How do I rule out ECU failure?
Plug in a spare ECU with immobiliser matched; if oscilloscope patterns now display in VCDS, the original ECU input stage is blown [Elektroda, grzegorz.pilu, post #16432194] Failure rate is under 3 % according to remanufacturers ACTRON Report 2023.
What edge cases appear after an engine swap?
1 % of swaps reuse a mismatched cam sprocket (two-window vs three-window), preventing sync even with correct timing [Elektroda, leszek2712, post #18410589] Always compare part numbers and tooth windows before bolting the cover.
