P0420 but front left cat rattles

The Gas and Diesel Engines - VQ40De, VK56DE, YD25DDTi, V9X, Transmission, Transfer Case, Oil, Differentials, Axles, Exhaust...

Moderator: volvite

User avatar
se7en
Posts: 71
Joined: Tue Jan 05, 2010 10:37 pm
Location: Vancouver BC

P0420 but front left cat rattles

Postby se7en » Wed May 26, 2021 10:59 pm

Like the title says, the error code is consistently coming up (tho i clear it) as P0420.
I ignored it for about 5 or 6 months now.
But about a month ago i started hearing the rattle - it is not a heat shield.
Had it up on a houst by a local mechanic and the rattle (hitting it by hand) is coming from the front driver catalytic converter - as if chuncks of metal or coins are loose in there.
But no rattle on the front passenger cat.
Should i replace both?

Just so you know about 3 years ago i replaced all 4 cats - they were super cheap!!!


User avatar
smj999smj
Site Admin
Posts: 6054
Joined: Sun Jan 22, 2012 11:13 pm
Location: Prospect, VA

Re: P0420 but front left cat rattles

Postby smj999smj » Fri May 28, 2021 9:28 pm

I would replace both upstream converters if I were you. They may have been cheap, but they only lasted 3-years, so...? I've had good success with Walker Ultra converters from Rockauto; mine are 7-yrs old and still doing good. I deleted my rear converters with Doug Thorley mid-pipes. I would also not put the job off much longer. Being that the variable camshaft timing is used to accomplish EGR, it's possible that broken bits of catalyst substrate can be sucked up past the exhaust valve, into the combustion chamber, where it can score the cylinder walls and eventually create an oil burning engine.

User avatar
se7en
Posts: 71
Joined: Tue Jan 05, 2010 10:37 pm
Location: Vancouver BC

Re: P0420 but front left cat rattles

Postby se7en » Sat May 29, 2021 11:08 pm

Thanks SMJ,
I don't know how many lunches I owe you already :)

I was about to get supercheap ones (USD 150 for both front at premierautoexhaust) but I will go with walkers - I plan to keep this truck for at leeast 5 more years.

Thanks again!


Return to “R51 Engine, Driveline and Powertrain”