Rain-Light-Humidity Sensor Activation Guide (Polo 6C GTI)

[Speedhunter]

Hello gents,
New here – so instead of jumping straight in with questions and contributing nothing, here’s a small guide I put together on enabling the RLHS sensor.

The story begins with me realising that my wipers were only operating in a speed-dependent intermittent mode, not true rain-activated/automatic mode. This was confusing, because I could clearly see a rain sensor mounted behind the windscreen, and even more puzzling that a 2017 car wouldn’t have automatic wipers enabled from the factory.

As usual, the internet was full of incomplete or incorrect information. To make things trickier, I’m using OBD11, which gives much poorer visibility of long coding compared to VCDS – but I still managed to get it working.

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1. Identifying the Sensor

First, I removed the centre mirror trim to confirm which sensor I actually had. In my case, it was a Rain–Light–Humidity Sensor (RLHS) – part number 5Q0 955 547B.
All wiring was present, so the missing piece was simply coding.

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2. Long Coding – 09 Central Electrics

My original long coding:

00 00 18 40 42 53 00 DB 4F 84 40 00 40 07 03 C8 10 00 5B 02 53 01 00 00 00 00 00 00 00 00

Updated to:

00 00 18 40 42 53 0A FB 4F 84 40 00 40 27 03 C8 10 00 5B 02 53 01 00 00 00 00 00 00 00 00

Understanding bits that needed to be comfirmed or set:

Byte 6, bit 1
- Rain light sensor, LIN_REGEN_LICHT_SENSOR
Byte 6, bit 3
- Lichtdrehschalter_mit_Nebellicht_bei_Assistenzfahrlicht, Yes
Byte 7, bit 0 & bit 1
- Coming/Leaving Home function is turned on
Byte 7, bit 5
- Light rotary sw. with AFL, Yes
Byte 13, bit 5
- rain_sensor_function, 1=installed
Byte 20, bit 0
- Door LIN, 1=installed
Byte 20, bit 1
- Roof_LIN, 1=installed

Above coding will also enable Auto Light Rotary Switch altought its not necessary to have it for enabling auto-wiping trough RLHS. Also error free with normal switch.

After applying the changes, disconnect OBD11, turn the car fully off (key out), wait a moment, then turn it back on and reconnect OBD11.

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3. Subsystem Coding – RLHS

Navigate to:

09 Central Electrics → Subsystems → RLHS

OBD11 will offer two options: Info and Long Coding.
Go into Long Coding, and you should see 3 bytes that need to be coded according to your car model and the functions you want.

In many cases (including mine), the coding may show something like:

40 18 DD

This is a perfect example of why the rain sensor doesn’t work even when the main 09 coding is correct.

Let’s break it down properly before giving "magic numbers”.

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BYTE 0 – Functional Bits

Bit 0
Highway Light Function active (from ~140 km/h / 90 mph)

Bit 1
Rain Light Function active

Bit 2
Rain Closing active (auto close windows/sunroof in rain)

Bits 3–5 – Light Activation Threshold
00 – Normal
08 – Earlier (+20%)
10 – Earlier (+40%)
18 – Earlier (+60%)
20 – Earlier (+80%)
38 – Control module NOT or incorrectly coded

Bits 6–7 – Rain Sensor Function
00 – Rain Sensor active (Standard)
40 – Rain Sensor inactive
80 – Control module NOT or incorrectly coded

So in my case, Byte 0 = 40, which literally disables the rain sensor – hence why nothing worked.

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BYTE 1 & BYTE 2 – Vehicle Platform Identification

These two bytes combined identify the car model.
For Polo 6C, the correct value is:

38 DD

Other examples:

88 5D – Seat Leon (SF)
18 5E – Skoda Fabia (NJ) / Skoda Rapid (NH)
80 5D – Skoda Octavia (SE)
88 DF – Skoda Superb (3V)
A8 DD – VW Golf (SG1/BA5/BE1/BX5)/VWPassat(3G)/VWTouran(ST1)

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Correct Coding for Polo 6C

Your full 3-byte value should be:

06 38 DD

Which translates to:

– Rain Light Function active
– Rain Closing active
– Light Activation Threshold normal
– Rain Sensor active (Standard)
– Vehicle: Polo 6C

Your sensor should now be fully operational, and at the very least your automatic wipers should work. Other functions such as auto lights/CH/LH, rain closing may require further adjustment in the adaptation settings, which I may cover in future.

Regards Speedhunter