Hey all, I’m getting a P0420 code on my 2006 F250 5.4L. Both cat temps are reading 1188°F, and I’ve got around 213k miles on it. Also dealing with an exhaust manifold leak on both sides. Anyone had experience with this? Any ideas on what might fix it?
P0420 usually means the catalytic converter isn’t cleaning the exhaust enough. Sometimes it’s the rear O2 sensor, but it could be the cat itself.
Marlow said:
P0420 usually means the catalytic converter isn’t cleaning the exhaust enough. Sometimes it’s the rear O2 sensor, but it could be the cat itself.
Do you think it’d help if I tried replacing the O2 sensor first?
@Alix
Yeah, give it a shot! If the sensor doesn’t help, it’s probably time to replace the converter.
Are you also noticing a loss of power? Sometimes that can mean the converter is plugged.
Tatum said:
Are you also noticing a loss of power? Sometimes that can mean the converter is plugged.
Yeah, it’s definitely been feeling sluggish. Should I try pulling out the O2 sensors and doing a test drive?
@Alix
Yep, take out the upstream O2 sensors and go for a drive. It’ll be loud, but if power comes back, that could mean the converter’s clogged.
With that mileage, it’s not unusual to have a clogged converter. Could also be adding to that exhaust leak you mentioned.
Ollie said:
With that mileage, it’s not unusual to have a clogged converter. Could also be adding to that exhaust leak you mentioned.
Makes sense… got this truck from an older guy, and I’ve been sorting out issues since I got it.
Any issues fueling up? Ford had a recall for certain models due to tank vent problems.
Frankie said:
Any issues fueling up? Ford had a recall for certain models due to tank vent problems.
Funny you ask—when I fuel up, it spits gas back unless I disconnect a hose. Read somewhere about a box under the bed that gets clogged?
@Alix
Yeah, sounds like the vent control valve. It’s on the charcoal canister under the truck. When it clogs, gas vapors don’t escape right, so you get issues filling up.
@Alix
Did you try cleaning it out, or do you have to replace the whole canister?
Micah said:
@Alix
Did you try cleaning it out, or do you have to replace the whole canister?
You could try disconnecting the hose from the tank to the valve and see if that helps. Sometimes the whole canister needs replacing if it’s locked up.
Seems like you’ve got a few things going on! Fixing that exhaust leak might help too since it can mess with readings.
Joss said:
Seems like you’ve got a few things going on! Fixing that exhaust leak might help too since it can mess with readings.
Yeah, it’s always something with this truck! Thanks for the advice.