Dealing with VAG Code 00668: Rain Sensor Not Initialized
You just replaced your windshield, or maybe your battery died, and now your automatic wipers are acting crazy. You plug in your VCDS or OBDeleven scanner and see it: VAG 00668 - Rain Sensor Not Initialized. I see this exact code in our shop all the time on VW, Audi, and Porsche models. Let's break down what this means and how to fix it without pulling your hair out.
What You'll Notice (The Symptoms)
When the rain sensor loses its basic settings, your car doesn't know how to read moisture on the glass. You will usually run into a few annoying problems:
- Wipers swiping at random times on a perfectly sunny day.
- The auto-wipe function completely ignoring heavy rain.
- Intermittent wiper settings defaulting to a fixed, timed speed instead of adjusting to the weather.
Why Did Your Rain Sensor Lose Initialization?
The rain/light sensor (usually the G397 module) sits right behind your rearview mirror. It gets knocked out of whack for a few common reasons:
- Windshield Replacement: If the technician didn't use the correct silicone gel pad or failed to recalibrate the sensor after installing the new glass.
- Battery Voltage Drop: A dead battery or a sudden voltage spike can wipe the module's memory.
- Wiring Issues: A pinched wire in the overhead console or a loose connector block.
Step-by-Step Calibration and Repair
Fixing the 00668 code usually comes down to a physical inspection followed by a proper recalibration using a diagnostic tool. Here is how I tackle this in the bay.
Step 1: Inspect the Gel Pad
Look at the sensor from the outside of the windshield. If you see air bubbles, dirt, or a milky white film between the sensor and the glass, software calibration won't work. You need to pull the mirror off, clean the bracket, and install a brand new sensor gel pad.
Step 2: Clear the Fault Codes
Hook up your diagnostic scanner. Go to Module 09 (Central Electronics), read the fault codes, and clear the 00668 error. Turn the ignition off, wait thirty seconds, and turn it back on. Sometimes a simple hard reset forces the module to wake up and re-establish communication.
Step 3: Run the Initialization Process
Still acting up? You need to re-initialize the unit. In VCDS, navigate to Basic Settings under Module 09. Select the Rain/Light Sensor from the drop-down menu and follow the prompts to reset the adaptation values to factory defaults. Make sure the outside of the windshield is perfectly clean and dry over the sensor area before you run this procedure.
Need Professional Help in the GTA?
Modern auto glass isn't just glass anymore; it is a complex network of sensors and cameras. If you are dealing with wiper issues after a bad windshield install, or you just need a fresh piece of glass put in right the first time, give us a call. At AlexWindshield, we handle the glass replacement and the technical sensor calibrations all in one go. We provide expert mobile auto glass services across the Greater Toronto Area, and we back every single job with a rock-solid Lifetime Warranty. We will get your sensors initialized and your wipers working exactly like they did from the factory.
