Hi Everyone,

i have a 2013 CLS550 with the stage 1 renn tech tune. I live in AZ and I went to smog my vehicle for the first time and it failed due to multiple systems not resetting. Took it to local dealer and they informed me there were no error codes and that likely the renn tech tune was deactivating the O2 sensors downstream from the catalytic converters. Contacted Renn Tech and after providing my VIN they confirmed the tune was indeed turning the sensors off.

Unfortunately so so far all Renn Tech has offered is to sell me a “new” $2700 tune that will turn them back on and provides same performance as current tune. My registration expires in 3 weeks so I need some help on any other options if Renn tech does not offer any other help.

thanks in advance!