FAQ
TL;DR: 1 mm washers can affect switch activation; "Do not remove the washer" cautions one helper. Verify switch reach versus gearbox trigger depth before changing parts. If you alter sealing, watch for leaks. [Elektroda, jacekwwy, post #17155157]
Why it matters: For Skoda Octavia I 1.9 TDI owners losing reverse lights after a switch swap, this gives fast, proven diagnostics and fixes.
Quick Facts
- Quick wiring check: bridging the reverse-switch connector illuminated the lamps, confirming the circuit and fuse were OK. [Elektroda, slaw777, post #17154900]
- Switch format observed: 2-pin reverse light sensor on the Octavia I 1.9 TDI. [Elektroda, slaw777, post #17155096]
- Measured plunger protrusion ~6 mm; threaded section plus plunger reach ~25 mm. [Elektroda, slaw777, post #17159583]
- Gearbox reverse-trigger depth measured ~31 mm; a 1 mm washer reduced engagement, removal restored function. [Elektroda, slaw777, post #17161804]
- Sealing note: OE sensor thread was glued; washerless install sealed with Loctite thread glue. [Elektroda, slaw777, post #17162676]
How do I quickly confirm the reverse-light wiring is OK?
Bridge the two pins at the reverse-switch connector. If the reverse lamps light, the wiring and fuse are OK. That points the fault to the switch or activation depth in the gearbox. This is the fastest zero-cost check before buying parts. [Elektroda, slaw777, post #17154900]
Why does the light work when I press the switch by hand, but not when installed?
Hand-pressing proves the switch and circuit can work. Failure when installed points to insufficient actuation travel inside the gearbox. Measure the gearbox trigger depth and compare it to the switch’s actuation reach using a caliper. Adjust spacing or switch type accordingly. [Elektroda, jacekwwy, post #17154994]
Does the supplied 1 mm washer really matter here?
Yes. In this case the 1 mm washer stopped the plunger from being pressed far enough. Measured trigger depth was ~31 mm, while the switch reach was ~25 mm. Removing the washer restored the reverse lights: "now it works nicely." [Elektroda, slaw777, post #17161804]
Should I remove the washer, or keep it for sealing?
A helper warned, "Do not remove the washer because it is double protection," preventing loosening and oil leakage. If you remove it, you assume sealing responsibility. Recheck for seepage after driving. When unsure, retain the washer or use proper sealing. [Elektroda, jacekwwy, post #17155157]
What are typical reverse-switch dimensions on the Octavia I 1.9 TDI?
Reported measurements: plunger protrusion about 6 mm. Combined threaded section plus plunger length about 25 mm. These figures help compare with your gearbox trigger depth. A mismatch can explain why a new switch fails when installed but tests OK by hand. [Elektroda, slaw777, post #17159583]
Is the correct reverse switch 1‑ or 2‑pin on this model?
A user-reported unit is a 2‑pin switch. Confirm by inspecting your connector before ordering. Matching pin count and connector style avoids fitment and contact issues that cause intermittent or dead reverse lamps. [Elektroda, slaw777, post #17155096]
How do I measure the gearbox trigger depth and compare it to the switch?
Use a caliper to measure from the threaded seat to the reverse-gear trigger surface. Then measure the switch’s actuation reach from the seat to plunger tip. If the trigger depth exceeds switch reach, adjust spacing or the part. "Start with the cheapest and simplest... the caliper." [Elektroda, jacekwwy, post #17154994]
Mahle/Mehle or Febi—whats better for the reverse switch?
Both brands appear in owner discussions, but function matters more than label. Measure activation reach and verify connector fit before committing. As one helper put it, "Take one that will work"—and confirm with a quick caliper check. [Elektroda, jacekwwy, post #17159152]
Do I need thread sealant if I omit the washer?
One owner omitted the washer and used Loctite thread glue to seal and lock the threads. That restored lights and secured the switch. Quote: "I put Loctite thread glue on the sensor thread." Monitor for any seepage after installation. [Elektroda, slaw777, post #17162676]
Could the gearbox reverse trigger be bent or misaligned?
It is rare but possible for the internal mechanism to deform. A helper estimated such failures at roughly 1 in 10,000. If correct sensor and wiring still fail, inspect the trigger mechanism’s motion and alignment before deeper repairs. [Elektroda, jacekwwy, post #17155157]
How do I fix no reverse lights when the new switch fails inside the gearbox?
Try this 3-step approach:
- Measure gearbox trigger depth from the seat (example reported: ~31 mm).
- Measure switch reach from seat to plunger tip (example: ~25 mm).
- Remove the 1 mm washer or change spacing so the plunger engages, then retest.
This resolved the issue for the poster. [Elektroda, slaw777, post #17161804]
My connector doesnt click on the new switchcould that cause issues?
Yes. A poor-locking connector can cause unreliable contact. One owner noted the new plug did not click like the original and found the lamps still failed. Ensure the connector fully seats and the latch engages for consistent operation. [Elektroda, slaw777, post #17154954]
What does ABS code 01314 mean on this car?
Scan results showed ABS logged 01314—Engine Control Module, "Check DTC Memory—Intermittent." This means the ABS saw an ECM-side fault. Perform a full scan, resolve ECM DTCs like immobilizer or timing issues, clear codes, and recheck ABS. [Elektroda, slaw777, post #17162890]
Is adding a manual reverse-light switch a good workaround?
It is not recommended. A helper joked about a friend’s manual switch and called it annoying every time. Manual control can also raise inspection concerns. Fix the actuation depth or switch fit instead for a compliant repair. [Elektroda, jacekwwy, post #17155174]
After removing the washer, how should I monitor for leaks?
Drive and periodically inspect the switch area for any gear oil seepage. A helper advised paying attention for a while after changes. If you see oil, reseal the threads or reconsider using a sealing washer per OE. [Elektroda, jacekwwy, post #17162632]
you can always buy the sensor 
the head does not hurt since the shrine, such a switch would be necessary during such an inspection 
but measure the caliper on the chest first