Pairing Webasto Telestart T100 remote with Mercedes-Benz factory installed heater

There is a lot of false information online about Mercedes-Benz auxiliary heaters. To set the record straight: you cannot pair a standard Webasto-branded remote to a factory-installed Mercedes system, and you absolutely should not pull any fuses to initiate the pairing process.

These instructions have been verified on 2010 GL X164 with factory option 228 and remote with part number A2218203797.

Hardware and Compatibility This applies exclusively to Telestart T100 remotes featuring the Mercedes-Benz logo and for vehicles with factory option code 228 or B24 (AUXILIARY HEATER) on the datacard.

If your vehicle has any other factory or non-factory heater than Webasto Telestart T100 these instructions DO NOT APPLY.

• A2218203797: Fits 228 optioned vehicles with delivery date between 2007-07-09 to 2011-08-11. Chassis types W164 (ML), X164 (GL), W204 (C), W207 (E), W211 (E), W212 (E), W216 (CL), W218 (CLS), W219 (CLS), W221 (S), and W251 (R).

• A1668201097: Newer version of above listed as compatible with B24 optioned vehicles with delivery date from 2011-08-11 to 2012-07-22.

• A2218200497: Older version without LCD screen used with Webasto Telestart T90, listed as compatible with 228 optioned vehicles with delivery date up to 2007-06-26 (Chassis # 062071).

• Battery: You need one quality lithium battery like the Varta V28PXL for A2218203797 and A1668201097. There is no readily available lithium batteries for A2218200497, get two high quality alkalines instead, like Varta V23GA. Always play close attention to polarity, you can see which way plus goes from small symbol in plastic casing of remote.

The Pairing Procedure

1. Unplug any OBD2 diagnostic devices from the vehicle.

2. Remove the key from the ignition. If you have Keyless-Go, move the key physically out of the vehicle's wireless range.

3. Press and hold the auxiliary heater button on your center console for about 25 seconds. Watch the button's LED: it will first turn solid red, turn off, and then start flashing red. Release the button when it starts flashing.

4. Now within 5 seconds press and hold the remote's OFF button until red led on car stops flashing.

5. Next release the OFF button and press and hold the ON button. Heater should turn on.

6. Release the ON button. The remote is now paired.

To test it, long-press ON until the remote's LCD displays "On" and the car's heater light illuminates. Test the OFF button the same way.

That is the entire process. No pulling fuses, and no more futile attempts at pairing incompatible remotes.

You can pair multiple remotes. Oldest ones will drop out if you try to pair too many. Maximum number based on Webasto docs is six. Not sure if same applies to Mercedes versions.