Hows it goin fellas. Had my car sitting for 3 weeks, came back and it had a hard time starting, idled rough for a few seconds and went to normal, then I had some real nice thick white smoke comin out the back and a check engine light. Eventually the smoke went away so I figure water probably built up. Drove it around for a while and reset the ECU, CEL went away. A little while later it came back, I reset it again and it was gonne for a while. Finally came back up. So I go to advanced auto and heres what they read me

P0606 - PCM Failure
P0456 - Evap Emissions control - small leak

The car runs fine when the CEL is up. Nothing out of the ordinary so I'm thinking P0606 is due to P0456. Any idea what this is is?

Also a few years back a branch had stripped the shielding off the wiring to my secondary o2 sensor, it would always throw a CEL whenever it rained because of the wires short circuiting. I wrapped it up in electric tape and it's been fine ever since. The weird thing is, when I clear this CEL I have right now, it seems to only come back when I'm driving through the rain, exactly how the CEL I had a few years back with the o2 sensor. Can the secondary o2 sensor be causing these two codes if water is getting into the wiring?

Go figure this would happen a few weeks before trading the tC in for the FRS

 

Just replaced the gas cap. Read on a different forum that the gas cap goin bad causes the P0456 code sometimes. Hopefully if the two are related I won't have either come back.

 

Just incase anyone searches this topic. A replacement fuel cap fixed my issues. 800 miles and still no check engine light, it's been down pouring over the past few days too. I understand the fuel cap fixing the Evap leak issue. No idea why its fixed the PCM failure issue. But if you get both codes thrown, try replacing your gas cap. 12 bucks at Advanced Auto.

ps: If this helps you please post. I'm curious how many other owners hit this issue.

 

Sorry no one was able to help you but thanks for updating with the solution for future viewers

 

oh please, Ive been around these forums enough, admittedly not enough recently, but i know if someone knows the answer they'll respond. At least now if someone has the same issue maybe this topic will be of some help haha. And I know how much searching helps. Maybe this'll help eliminate future questions.

 

I'm afraid this didn't help me. I have the p0456 and I've had the code since like 100 miles after buying the car in June. I replaced the cap last month and while its helped my fuel economy a very slight bit, the light is still there

 

take a look at your fuel filler neck, this is the part where the gas cap gasket tightens against. If you see any corrosion of any kind, you'll need to lightly sand the filler fuel neck lip. I had that issue, and i stuffed a rag into the filler neck, to prevent any debris entering the gas tank, and i sanded with 200 grit garnet sandpaper, no more issues after that. What I found is that the gasket isn't sealing against the lip with the corrosion there (obviously).. no seal = no pressure = leak = cel.. hope that helps ya..

but this only applies if you've used a toyota cap, not some aftermarket, not all aftermarkets work on the tC.