endedobvious

Hi all, I just recently thought I resolved an issue where my 99 TL had the TCS and ABS lights on, at first only when I turn the wheel, and then later all of the time. We replaced the driver's side ABS sensor since the wire was partially torn, and that seemed to fix it for a day or so. It drove much more smoothly after that, and my transmission seemed to have fewer hard shifts afterward. The next day, about 50 miles in, my check engine and TCS lights are on. The code read is P0051. Last night I turned it off, and ~50 miles in again, they're both back on.

I've been having *some* transmission issues, but it's not too bad right now. I'm at 240k miles, and on my 2nd transmission (pulled a used one from a yard). The last one had horrible issues with slipping and shifting SO hard, all of the time, to the point that it broke 2 sets of mounts. Thankfully it never got into "limp mode" prior to me replacing it. This one isn't that bad, just slipping or a hard shift into 2nd here and there.

From what I can tell, the O2 valve is reading properly on the voltage, but it's not placed in the standard location since I have an aftermarket catalytic converter. I'm sure that has something to do with this, but quite frankly I'm not sure where to start with troubleshooting. The other issue is, why is my TCS light coming on with it? Any good suggestions? Thanks!

endedobvious

As an update, there's now a P0131 code along with the TCS. I'll have to do some more troubleshooting with the O2 sensor. Any ideas on why the TCS light is on now, though?

DP01TL

I tought that anything that affected power output (and a P0131 lean O2 code would most cerftainly affect power) basically shuts off the TCS system from the vantage point of, "it cannot control power output to the ground in less than 'normal' operating conditions".

So, anything that affects the ability of the engine to modulate power applied to the ground properly would cause that to happen. That is why transmission codes also shut off the TCS system as well.

It isn't just this car that does that... I thought ALL modern vehicles that have stability control/traction control/etc ALL do the same thing. I know my Cadillacs and Lincolns all do that as well. I own a 2015 ATS, a 2014 CTS along with a 2012 MKS and a 2017 MKT.

whitetiger5

TCS and (on the type S) VSA lights usually come on with any Check Engine Light error. Your DTC of the H02S sounds about right; I would test and replace it if necessary; rock auto sells the Denso version which is a great replacement, as well as the socket to fit over the existing to take it off. there is a 5% coupon code if you search.

endedobvious

Thanks, rock is my go-to. I'll be sure to check out the Denso one.

endedobvious

My bad, the more you know. Last time I had O2 sensor issues, I didn't recall the TCS light, but that was a few years back. I'll keep that in mind, thanks!