dreaded p0420 Yes, i searched. maybe i am doing it wrong?

G

gshadow325

New member
Yes i searched and searched for a answer but i just cant find it! so many threads out there but none of them are close.

My p0420 problem on my 2003 v8

I changed both bank one sensors front one with OEM red box toyota, rear first with a cheapo unit, then with a denso unit. now its a oem in front bank one and denso rear bank one.

I also changed all new plugs to ngk iridiums, no change. code still comes back.

here is live data via a elm327 BT dongle and using the torque app on my phone


i dont think its a cat issue. i dont want to keep throwing parts at it and hopefully something fixes it.

I am considering the MAF, but needed info on what MAF to buy that is almost the oem red box but without the price tag.

Suggestions anyone?
 
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You can try a re-manufactured one from O'Reilly. I bought one for my 2006 V6 and it worked fine.

Here's the Link to the MAF sensor (part # 74-50021) for your 2003 V8 for about $70.

If it does end up being a bad cat, I would definitely go to a exhaust shop and go the aftermarket cat route. You can save a bunch of $$ vs. going to a dealer and buying the OEM cat.
 
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would messing with the yaw calibration stuff set off a 420 code?

just came back from under the car. to check connections and verify the sensors are in tight. YES they are LOL
 
cgl4au said:
You can try a re-manufactured one from O'Reilly. I bought one for my 2006 V6 and it worked fine.

Here's the Link to the MAF sensor (part # 74-50021) for your 2003 V8 for about $70.

If it does end up being a bad cat, I would definitely go to a exhaust shop and go the aftermarket cat route. You can save a bunch of $$ vs. going to a dealer and buying the OEM cat.
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dont have orieleys up here in pa
 
ordered same part from autozone just now. i will get it in 2 hours. $52.50 wholesale price and free delivery and no tax. :P

hope this fixes it..going to run some live data on the maf first right now before i change it out.
 
Did you try cleaning your old MAF? There is a special cleaner to do that. When the MAF gets drirty or oil on them the dont work correctly. If I remember correctly the tiny wires heat up from the current that passes thru them. The mass of air flowing over them cools them and the current changes therefor measuring the amount of air flow. Periodic cleaning keeps everything correct.
 
so yesterday. i went under the truck and tighten up both front and rear bank one sensor. did a clear ecu and light came on, on the way home. cleared it last night.

this morning, dumped a whole can of seafoam in it before 1st start of the morning. car has little less than 1/2 tank of fuel.

this morning scans right after start up


after warm up.


after i stopped for 1 hour and restart


Installed the new remanufactured MAF from A1 Cardone part # 74-50021
and this is what i got.


So i am confused on what went on. I dont know if it was the sensor not on tight enough? the rear i put on tighter than the last time it came off. the front bank one is a PITA to get to so i made it tighter than it was. to the point i was scared it would break. i manage to get another 1/4 - 1/2 more rotation.

Would it be the seafoam?
Would it be the sensor is not on tight?
I dont think its the MAF because i didnt install that till this afternoon, right before the last live reading.
 
Sea Foam in the tank usually takes a little while to gain the full benefit, but I guess it's possible. However, it sounds more like the tightening the sensors may have done the trick. Perhaps a loose connection in the o2 wiring harness?? Hopefully the CEL will stay off this time. Based on what you said, it was likely not the MAF sensor, but at least you know that you have a working one :).
 
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cgl4au said:
Sea Foam in the tank usually takes a little while to gain the full benefit, but I guess it's possible. However, it sounds more like the tightening the sensors may have done the trick. Perhaps a loose connection in the o2 wiring harness?? Hopefully the CEL will stay off this time. Based on what you said, it was likely not the MAF sensor, but at least you know that you have a working one :).
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i didnt unplug the front sensor, just wen it and wrenched it tighter. same with the rear sensor. i think you are right about tightening it though. lets see what happens for the next 100 miles or next fill up.
 
gshadow325 said:
i didnt unplug the front sensor, just wen it and wrenched it tighter. same with the rear sensor. i think you are right about tightening it though. lets see what happens for the next 100 miles or next fill up.
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Definitely keep us posted. Hope it all works out for ya!
 
updates:

well my battery has been dying the last few days. so i took my backup battery out from my convertible..installed it in my 4runner

Stinger SPP1700
spp1700.jpg


fits like a glove LOL

did this this morning so i dont know if its a voltage issue with my 4runner.

it seems ok right now.
 
instead of leaving this thread open ended.

Update:

Since the battery install i have gotten Zero codes and the truck has been running cleaner. here is the snap shot from this morning



here is the DTC readiness...since its ready to be scanned since the last reset. i think alot has to do with the ECU itself had to be reset in addition to clearing the codes.


i think my battery dying was good because of two things. 1: it reset the ecu 2: i gotz moar battery powa!

now moving onto next mod....Train Horns & Train Horn Kits: Loudest Horns Available, look for the thread :)
 
gshadow325 said:
instead of leaving this thread open ended.

Update:

Since the battery install i have gotten Zero codes and the truck has been running cleaner. here is the snap shot from this morning



here is the DTC readiness...since its ready to be scanned since the last reset. i think alot has to do with the ECU itself had to be reset in addition to clearing the codes.


i think my battery dying was good because of two things. 1: it reset the ecu 2: i gotz moar battery powa!

now moving onto next mod....Train Horns & Train Horn Kits: Loudest Horns Available, look for the thread :)
Click to expand...

Good to hear :thumb3:! My 4R actually had a dead battery a week after I purchased it used. Conveniently, while we were 200+ miles away from home for a family vacation, it started stalling at a red light (at low rpm) less than 5 miles from our destination. Come to find out, it was putting out around 300 cca. I'm surprised it even started that day. Anyway, we basically made it all the way to our destination on the alternator...lol. Never hurts to have a fresh battery!
 
Update:
I got the code p0420 again. Fixed that by buying a pace setter header $233 + 50 for head studs and nuts. Driver Side install, muffler and muffler tip cost me $225.

After the driver side install, I started getting p430 code. Swapped out both passenger side o2 sensors. Still got the code. Did some driving with the rear Window cracked a little open and sunroof fully open. This was to draw in some occasional exhaust smell to see if I got any rotten eggs smell. Yes I did, so that means bad cat on passenger side just like the driver side.

So right now here is where I am at chasing these p0420/p0430 codes.

Two pace setter exhaust $233 +265 manifold.
All four o2 sensors (one oem, 3 denso) $325
16 head studs $100
16 head bolts
One felpro exhaust manifold gasket set. $35
Labor $500

Holy Crap! $1425 later I might have a cel free dash.
 
gshadow325 said:
Did some driving with the rear Window cracked a little open and sunroof fully open. This was to draw in some occasional exhaust smell to see if I got any rotten eggs smell. Yes I did, so that means bad cat on passenger side just like the driver side.
Click to expand...

Not necessarily, most of us have stinky exhaust with good cats. Apparently it's a Toyota thing but a search will turn up plenty of threads on the topic. Seems a lot of us just turn the tailpipe out the side to help alleviate sucking it in with the back window open.

Either way, sorry the PO420/30 is giving you such grief. I only had to do a new cat and O2 sensors on one side to get rid of the error. Probably didn't need the cat but I thought I knew more than some people posting it was just the O2 sensors.
 
You know what sucked?

Finding someone that will do it. My usual mechanic dragged his feet. This is how much he dragged his feet, I left him the truck on a Thursday night, went on vacation that following Sunday thru to the next Tuesday, total of 12 days at his place (8 working days). When I got back from vacation he said he ran out of acetylene gas for his torch so he can't get the bolts off. Asked two other mechanics I know. Both said oh this oh that. I said what ever and went on my way.
Finally went on the spur of the moment to my favorite muffler place, guy I have been using for 15 plus years. Asked him to do it, @130pm was out by 430 and $225 later.

It didn't end there, on the ride home I get p0430. Reset it and it came back a few days later. Then two pass side sensors later. ...p0430 code again. Now today I get my pass side from Amazon and dropped by to see him again, $180 later I am out in 3 hours. I hope it's done. I do honestly believe that the previous owner did not ever change the plugs since it was new and that caused the cats to go bad. Plugs were in bad shape when I took them out.
 
gshadow325 said:
I hope it's done. I do honestly believe that the previous owner did not ever change the plugs since it was new and that caused the cats to go bad. Plugs were in bad shape when I took them out.
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I feel your pain. I had a cracked passenger manifold that was driving me crazy. I spent the bucks and replaced both manifolds with the Pacesetters. I started getting P0420 on the driver's side, so I replaced the original A/F and O2 sensors with Denso. I thought that would take care of it, but that damn code kept coming back after about 70 miles or so.

I started monitoring the sensors with Torque on my android tablet, and could see that the downstream O2 sensor was bouncing way too high compared to the A/F inputs. I decided to try the spark plug anti fouler plug trick. Drilled it out, installed the O2 sensor in it and saw that the signal dampened a lot. I've been CEL-free ever since!

That might be a backup plan for you, since I hear that the Toyota ECUs are sensitive to our higher flow cats.
 
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