Any ideas? Anything helps

These two codes showed up at once. I cleared them and they both came back at the same time. Any help?

 

C1201 is likely caused by P0430. It would mean the engine has a fault, so traction control is disabled. It is a common Toyota/Lexus event. So, address the P code. Something is bad in bank 2. Could be leaking exhaust gasket, cracked manifold, bad O2 sensor, bad cat, etc…

 

the engine fault is for a bad cat, but why would that turn off the traction?

 

Don't know. Can only confirm it happens on many seemingly unrelated codes. Seen that on my 07 Tacoma and daughters 20 RAV4 and other forum member’s vehicles.

 

According to chatgpt:Toyota disables traction control for many “unrelated” codes because:

• TRAC/VSC relies on accurate data from multiple systems
• Any fault that affects engine torque, braking, or sensor data compromises safe operation
• Toyota uses strict fail-safe logic, shutting the system down entirely rather than risk incorrect intervention

 

This is correct, the VSC/TRAC system needs accurate information to operate correctly. If the CEL is set for any reason, it triggers C1201 which disables VSC/TRAC until the issue causing the engine code is corrected and the engine code is cleared.

One issue can and often does cause more than one diagnostic code. These codes are very much related, but fixing the issue will resolve both codes.

Jeff

 

well, im not gonna buy a whole new cat for this car so guess im screwed

 

You could put spacers on the downstream oxygen sensors. This would get rid of the code. Off-road use only and all that jazz. https://www.oreillyauto.com/shop/b/i...r/ebd2ebf2935a

 

Cats could be fine. An auto diagnostician will look at your long term fuel trims, among other things, to check the O2 sensors and other components to determine the actual cause of the code. A muffler shop can check for a restricted cat and check for exhaust leaks.

 

after driving to uni and back the light went away so now I'm confused

 

It is likely that the component at fault is at it’s boundary limits. Like on a teeter totter, good on one drive cycle, bad on another.

 

There's a very good chance that this is a downstream oxygen sensor issue and needs to be replaced. That said, just throwing a sensor at it would be throwing away money if the cat is actually the issue. A proper diag would give you the answer to that question.

But also, if you can get a sensor for less than the diag cost and replace it yourself, you'd be ahead if it does indeed just need a sensor. Something to consider. Denso is the original sensor supplier and offers relatively low cost aftermarket OEM sensors.

Jeff