CEL Code p0420?

[RichD978]

any ideas? guessing i need to replace a o2 sensor? Can the longo hero or anyone else shine some thoughts ?

got the code once, erased it and came back on 200 miles after

[djsaltine]

Jeff prolly has your back on this one.

If ya asked me, your car wants to chief 04:20

[Jackass-Jeff]

P0420 – Catalyst System Efficiency Below Threshold (V-6 engine)

· Three-way catalytic converter malfunction
· Open or short in heated oxygen sensor circuit
· Heated oxygen sensor malfunction

Your o2 sensor in the exhaust piping is bad, there is a short circuit/open circuit from that o2 sensor to your ecu, or your cat. converter is bad... check your emissions warranty. it may be covered for 8 years/80.000 miles (if it's the cat. converter). If it's the o2, just buy one and replace it (it's easy since you know which one)

I made the Tutorial for OBD-II codes a sticky for future reference.

[SC V6]

Get a o2 simulator...

[RichD978]

whats that

[Fletch]

The post-cat O2 sensor's function is to make sure the cat is doing it's job correctly, it does not affect closed loop fuel trim and what not. The simulator basically fools the ECU so you don't get a CEL.

Something like this may work for us.

https://www.casperselectronics.com/Merc ... ode=toyota

[Jackass-Jeff]

I don't know how strict the smog/inspections are in MA... I would check before investing in an o2 sim instead of the actual repair =P

[SC V6]

yeah... u will probably not pass emissions testing if you don't actually fix the problem.. if you have no testing like me.. just gut the cat and get a simulator

[SpeedySolara]

I got the same code on my car and it these are some probably causes according to the diagnostic:

1) catalytic converter defective
2) engine misfire or running condition
3) large vacuum leak
4) engine oil leakage into exhaust-valve guide seals, piston rings

I still haven't gotten an official diagnostic from Toyota but I'm concerned whats the worst case scenario if I continue driving my car with the diagnostic I got. Honestly the motor sounds fine when I rev it up and even while driving but I figured I'd get some input on this.

[Akfahad]

when I got the code, my heater function on the 02 sensor was shot, needed a new one.

[Eye8Pussies]

worse case scenario, the o2 sensor gets worse- and chances are that it's done for anyway, so it won't matter

change the sensor first before looking at anything else, unless you start throwing other codes as well, such as lean/rich/misfire codes, etc.