I have a 2003 3.2 CL with 70K, and recently I was driving and after 15 Min,since starting engine, simultaneously the amber TCS light and amber Malfunction Indicator light came on. Was traveling highway speeds and there was no performance degradation that I could tell. Continued to drive and lights stayed on. After turning off ignition for a short period of time (15 mins) restarted engine the TCS light was off, but MFL was still on. After driving for approximately 10-15 mins the TCS light came on and stayed on, until the next time I shut off engine and then after a short period, restarted engine, drove for a short period and the TCS light came back on, stayed on while driving. This process has been repeating. The brakes do not feel hot. Coincidentally, this all started after using AmourAll brake dust repellent, and was wondering if this could be the culprit?
Mechanic did diagnostic check and only fault (at least thats what he said) is O2 sensor, but doesnt seem to make sense. I've seen lots of potential problems here from EGR to PCV to TCS circuits to Intake to Xmission, but no definite problem and solution. Any help would be appreciated. Thanks

 

Are the two O2 sensors original to your 70K mile 19+ year old car?
If so, consider having them changed out.
You can get both Denso appropriate sensors for less than $100 before shipping from RockAuto.com.
The O2 sensors in my automatic 51K mile '03 CL-S, when purchased in Nov 2019, ran much better when I changed the tired OEM originals.
Good Luck!

 

Why did you have a mechanic diagnose your car if you weren't going to trust him anyways? I agree an O2 sensor shouldn't trip the TCS light, but did you discuss that with your mechanic?