Help Diagnose Code

[PLDXSR5]

Engine light came about four days ago. Finally had time to take it to a shop to get a free diagnosis. Attached are the print outs I received.

Any input would be greatly appreciated!

https://flic.kr/p/LVqNUY
https://flic.kr/p/MSVKcR
https://flic.kr/p/MSVKNv
https://flic.kr/p/LVsr4Z

 

[Fit4Action]

Engine light came about four days ago. Finally had time to take it to a shop to get a free diagnosis. Attached are the print outs I received.

Any input would be greatly appreciated!

https://flic.kr/p/LVqNUY
https://flic.kr/p/MSVKcR
https://flic.kr/p/MSVKNv
https://flic.kr/p/LVsr4Z

P0420 almost always means a Catalytic Converter.

Part # TOY93261

That's the front one that is monitored.

List price $918.49

Might be able to pick one up at your local auto parts store for maybe 400ish. My cost as a shop is $420

Best of luck. :dancin:

 

[gamefreakgc]

Don't buy a catalytic converter yet. What you'll want to do is replace the rear O2 sensor first, that's the sensor that throws the P0420 code. They only have a life of about ~90k miles, per Toyota.

They are around $45 on Amazon, just make sure you buy the right one for your year and driveline (2WD vs 4WD). Easy to replace, but if you have rust then be sure to hit the area with penetrant a day before. Then either drive it a few days or pull the EFI fuse in the engine and see if the codes come back. If not, you just saved $850.

 

[gamefreakgc]

Anyone know if this is the front or rear sensor?

https://www.amazon.com/Denso-234-9002-Fuel-Ratio-Sensor/dp/B000C5YCYS

That's the front. Be sure to order the right part, you can double check the DENSO part number for your application on their website.

 

[mtbtim]

The FIRST thing I'd do is just clear the code and see if it comes back. I've now gotten this code twice with my truck while on two different trips. In my case, I think it might have to do with driving in changing elevations because both times I was driving in much higher elevations than I live at. I live near sea level in San Jose, CA and I've had the code pop up when driving in the 5000-8000ft range above sea level and both times on longer trips. It wasn't just a quick trip up to mountains and back home. It was times when I spent 2+ weeks driving at higher elevations than I normally do and driving the truck for long distances.

If the code comes back, the SECOND thing I'd do is follow [MENTION=115347]gamefreakgc[/MENTION] advice and replace the rear O2 sensor.

If the rear O2 sensor doesn't do it, I'd live with the code and just clear it out before you have to bring it to a place to get the smog certificate done for your registration. I had a code like this for my Subaru Outback and a dealer suggested I replace the catalytic converter. After I got the price tag shock, I said screw that and just drove it. It passed smog every time.

I would ONLY replace a catalytic converter as an absolute last resort if you can't get your truck to pass smog. They're just too freaking expensive.

 

[gamefreakgc]

Unless you have a spare one laying around your backyard like I do . I almost didn't pass on this last test so I think I'm going to keep this one for myself instead of sell it.

 

[PLDXSR5]

Wow. I appreciate everyone's feedback!

So I just looked over the service records that came with the vehicle when purchased it in May..

Dating back to 11/8/2010, the 4runner was diagnosed and the fault code #PO420 is seen on the invoice. The shop traced and located the problem to oxygen sensor which was blown out of exhaust pipe. One hold down stud was broken, so the shop retapped other stud. Then secured the oxygen sensor in exhaust pipe.

On 11/15/2013, the fault code #PO420 reappeared and was described as the "cat below threshold" on the invoice. The shop removed broken shields on exhaust system.

Lastly, on 11/18/2013, again the code came up. Recommends owner to replace the oxygen sensor.

The rest of the records I have don't list a oxygen sensor being replaced. So you guys hit the nail on the head.

So rear O2 sensor it is.

Should I replace both, or stick to the "if its not broken, don't fix it" motto?

Finally, once I replaced the sensor, how do you reset the system?

 

[PLDXSR5]

Bump

 

[jgue467]

For now I would save some coins and just get the rear one, its less expensive than the front which really is an "air/fuel trim" sensor (more range of adjustment).

Mine suffers from what 4R#3 says an occassional 0420 and Always is thrown when driving offroad on slightly to moderatly bumpy roads just putzing along at 5mph, never when i'm driving "normal" in city/highway. Maybe I should throw the rear one on. Hmmmm. :cowboy:

 

[TheDurk]

For now I would save some coins and just get the rear one, its less expensive than the front which really is an "air/fuel trim" sensor (more range of adjustment).

Mine suffers from what 4R#3 says an occassional 0420 and Always is thrown when driving offroad on slightly to moderatly bumpy roads just putzing along at 5mph, never when i'm driving "normal" in city/highway. Maybe I should throw the rear one on. Hmmmm. :cowboy:

It's not the bumps, it's the speed. Mine would throw a P0420 whenever I visited this State Park in Maryland that had a 10 mph speed limit throughout and was famous for enforcing it. The roads were asphalt and pool table smooth.

Definitely try the rear sensor first. If it doesn't work, and you have 80k or more on your front, do that one, too. They degrade without throwing a code and your mpg starts to slip over that so it is worthwhile anyway. Also check carefully for exhaust leaks from the rear sensor forward. Can be a cheap fix.