Stolen Cats leading to Evaporative emissions codes

I had my catalytic converters stolen and replaced. Driving away from the exhaust system repair, my 2003 Tundra started throwing codes for evaporative emissions that had never appeared before.

Codes are P0441 and P0446 as I recall. P0442 as well, but that one had appeared before occasionally.

Does anyone here have any correlation of those codes to the catalytic converter theft. I have a hard time believing that the first time these codes appear is the first drive after the cat theft and the two are unrelated. In 203,000 miles these codes had never appeared and it has to be a 1 in 10 million chance that it is random.

Is there something about the engine running with no catalytic converters in place that would cause this?

Any help in this mystery would be greatly appreciated. The scum-bag insurance company of course does not want to cover anything without a fight. The only thing they do without a fight is cash the check every month!!

 

All of the codes you provided are EVAP system related - i.e. tied to fuel/emissions. Most commonly it's because someone didn't install the gas cap fully, or for your year there is also a TSB for the fuel filler neck that tends to crack.

I highly doubt it has anything to do with the cats. Did they happen to cut the O2 harnesses for the cats? If yes, did you start the truck before you realized the cats were stolen?

 

I did not know they stole the cats until I started it. Then had to run it to get it on the tow truck, as well as a very short drive to be repaired (less than a mile).

I don't think they cut the harness - but that was all fixed by the exhaust shop.

 

Did you replace them with factory cats/o2 sensors? The cheap knockoffs will throw codes.

 

The upstream is, I think, installed in the cats, but maybe they cut between the sensor and capsule.

Definitely this, if not using Denso brand sensors, codes can happen. But I wouldn't expect to see 3 EVAP codes that are consistent with this TSB for his model year. off-brand/counterfeit/faulty O2 sensor codes tend to throw for cat efficiency or O2 circuit/heater malfunction.

 

I had a random evap code show up intermittently, then all the time when my rear O2 gaskets were leaking.

Since they got repaired it hasn't come back.

No idea why but it happened.

 

Did they slice the evap. purge line while cutting out the cats by any chance?

 

There are not any OEM Cats available.

 

No one has mentioned that. Will have them check.

 

OEM whats?

This is the other thing I'd be looking for and I failed to get at earlier - @FlyingToys understanding what EVAP system is may help you understand what you need to be looking for.

Your fuel delivery system is a closed/sealed system which needs to have an exact amount of vacuum. Think of it as a piped circle between your gas tank and the engine which delivers fuel and holds vapors. Along that piped circle, there are purge/vents and a canister with charcoal in it to catch extra stuff.

The ECU monitors how much pressure is in the system. Obviously, if you're sucking fuel out of the tank to be burned at the cylinder, as fuel comes out, vacuum builds up. When the fuel system vacuum reaches a certain pressure level, the ECU will fire off one of the purge/vent solenoids to release pressure. But this system relies on having a SEALED system to work correctly. So, say the gas cap is faulty. Or say there's a crank in the fuel filler neck as is explained in that TSB. Suddenly you have an air leak, and it's difficult or impossible to hold enough vacuum in the lines.

That's what those codes are telling you - you have a leak and/or the ECU suspects the vent/purge valve is stuck open, and therefore you can't keep proper vacuum/pressure in the lines.

The fuel/vapor lines between the gas tank and engine run along the framerail in our 1st Gen trucks, IIRC. What landphil is suggesting is, when they cut the cats out, they may've nicked or severed one of those lines and that's why you're seeing this. However, simply unplugging a specific hose under the hood will do it too.

 

Gaskets on rear O2 Sensor?

 

Like here - this guy had one of his lines disconnected, related to EVAP system. https://www.tundras.com/threads/weird-engine-noise.127280/#post-3249739

Something as simple as that line getting unplugged would generate the codes you're seeing. Or if that same line was cut/disconnected somewhere under the truck.

 

That is very helpful background info - I don't know much about modern cars! Appreciate the help!

 

Rear O2s have a gasket between the pipe flange and the sensor flange.