04 LC100, P0420 after driving for about 50 miles (1 Viewer)

[odessit]

Got 165k on 04 LC100
Replaced oxygen sensor 1/bank 1 last year, sensor 1/bank 2 few weeks ago - both were shown as errors P0135 (?) and P0051 in OBD II
Reset all errors. Now I get P0420 after driving about 50 miles. Sometimes check engine light (and VSC Off + 1 more) comes on sometimes it does not. I reset the code, drive 50 miles - get an error again.
EVAP canister was replaced at around 60k.
Got new rear muffler few months ago. Whole exhaust from CAT to the end was replaced at around 60k.
What is the best way to approach this issue?
Replace O2 sensors 2 (after the CAT)? Measure voltage? Try premium gas (I am running on regular)? Something else?
I need to pass inspection and really do not want to be spending money on EVAP canister and/or Catalytic converters.

 

[2001LC]

Make sure engine is reaching operating temp. Is coolant to top of radiator, and reservoir to low line at minimum. Bad thermostats can be hard to detect sometimes, one test; is cabin heat getting really hot, it should.

 

[odessit]

Thank you. Will check the coolant and heat. I am pretty sure tempreature gauge seats right in the middle of the range.

 

[vipergrhd]

Did you replace it with a Denso part?

 

[odessit]

Yes. replaced using Toyota OEM 89465-60150 - did not replace myself - had a shop which works on my cars do this. Oddly enough I am having the same problem in my ES300 after replacing O2 sensor... I do trust the shop - likely to be a coincidence.

 

[SWUtah]

Try a new OEM gas cap.

 

[odessit]

Should I switch gas caps between my GX470, 07 and LC100? GX has no errors - knock on wood. I assume these are identical. Or just go and buy a new one?

 

[SWUtah]

Should I switch gas caps between my GX470, 07 and LC100? GX has no errors - knock on wood. I assume these are identical. Or just go and buy a new one?

They are cheap, buy a new one.

 

[odessit]

I will. GX's would not fit anyway. Do dealers stock quality ones or should I order by Toyota part number?

 

[Spike555]

You cannot tell if the engine is at proper temp just by the gauge on the dash, gauges on the dash are there for looks and emergency warning, they are calibrated to read normal 99% of the time no matter what.
You need to check engine temp with a OBD II scanner that reads live data, you can rent one from a auto parts store.
The most common reasons for O2 and cat codes on virtually all cars is the need for a tune up, engine running to cold, clogged air filter, cheap fuel but not always in that order.

 

[Sandroad]

I think if you replace both downstream O2 sensors and reset the code you'll be fine. I think you have one bad downstream sensor and you may as well replace both.

 

[odessit]

Replace downstream sensors even if there are no codes thrown by the sensors? Or only one from Bank one - the one which throws the code? I do not mind spending money, but hate throwing money away. In particular on something that is unlikely to change the way car drives. Only to comply with emission regulation.
On other items - Air filter was replaced within a year and I do not drive much; gas... was using Mobil for last two tanks. Have to say - used local gas station for awhile as it is cheaper or more in line with the rest of fuel prices. I beleive spark plugs were changed around $100k. Should be good for $100k. No? Something else to tune up?

 

[Sandroad]

You could certainly start with just the one sensor, but they are cheap and once the truck is "under the knife", I'd do both. No real "tune-up" involved in modern engines. Just things like plugs and MAF sensor cleanings and such.

 

[2001LC]

***I do not drive much; gas... was using Mobil for last two tanks. Have to say - used local gas station for awhile as it is cheaper or more in line with the rest of fuel prices. I beleive spark plugs were changed around $100k. Should be good for $100k. No? Something else to tune up?

How long does it take you to use up a full tank of gas, Weeks - Months?

 

[odessit]

How long does it take you to use up a full tank of gas, Weeks - Months?

It takes 1-2 weeks to empty a tank. Why do you ask?

 

[looking4lc]

i have p0430 and cleared it twice, 2 O2 Sensor on the way.

 

[odessit]

Coolant tempreature shows at 90 degrees Celcius on OBD II (194 Farenheit). Does it sound about right? Or should I look for a different measurement?

 

[odessit]

Drove about 150 miles after reseting codes. No 0420, but indicator shows Stat. EVAP System: Not Complete. How many miles am I supposed to drive to have it Complete? Bought new toyota gas cap today - $30. Will put it on if code shows up.

 

[Sandroad]

Coolant tempreature shows at 90 degrees Celcius on OBD II (194 Farenheit). Does it sound about right? Or should I look for a different measurement?

My Scangauge reads 196F all the time.

 

[odessit]

My Scangauge reads 196F all the time.

Thank you for information! I got a cheaper one... But 194F sounds about right then.