Hi

A few days ago, the MIL codes P0440/441/446 showing up in my 2000 Toyota Camry. This has happened to me about 4 years ago and was fixed by replacing the VSV next to the canister. I had also replaced the gas cap that time.

I go the code again last month. This time replacing that VSV did not fix the issue. The code returned a few days later. So I decided to do a thorough test -borrowed a vacuum pump and tested all the VSV's (there are 3 in my model) as per Chilton's instruction - they are all good. The hoses look good too - at the front side at least.

Continuing with the other tests will require removing the canister, which is a bit challenging.

Can anyone suggest any other possibilities? Has anyone faced this issue?

Appreciate the help.

 

Others have had this problem.

Suggest a search of this and the Toyotanation site for past posts such as the one below:

https://www.camryforums.com/forum/ge...41-p0446-4442/

 

I checked the connectors as mentioned in the other post - they look good. I also read the voltage at the front connectors when the key is tuned to ON position. Both connectors in the front read 12 volt.

I did not mention the gas cap in my last post. After the car was sitting around for a few hours, I opened the gas cap. There was a short hissing noise - couldn't tell if the air passed in or out. I am thinking, this probably means the gas cap is good and the tank is not leaking.

 

If you read the link in the above post there are a host of issues that can cause this code.

Troubleshoot P0446 code first.

Issues could be VSV's.
leaking hoses.
Wiring issues.
Cracked canister.
Bad vapor pressure sensor.
Leaking overfill check valve.

P0440 means fuel tank pressure is atmosphere after 20 minutes of driving (air leak). If no air leaks and the VSV's are good perhaps the pressure sensor is bad.

 

Thanks Joey.

I replaced all the hoses around the valves in the engine compartment yesterday. The new hoses do feel much more tighter.

I will check the other points you mentioned over this weekend - will post updates.

Couple of questions:
1) How do I get to the fill check valve ?
2) Does a new canister come with a pressure sensor?

Thanks.

 

I tried a few other things without results.

This week I took it to the dealership, they did a pressure test and told me the gas cap was loose.

I replaced the gas cap and the code is reset - hope this fixes the issue.

 

This reinforces my rule of thumb, always check/tighten/replace the gas cap before trying anything expensive. Hope it works.

 

here's excellent write up to recap the cap:

The GAS CAP code!!!!!!!!!!!!!!
The dreaded GAS CAP code!!!

I see many posts here about how to fix ( the dreaded GAS CAP) EVAP codes. Today I am going to educate you as to the functions and diagnostics involved in Evaporative Emissions issues and what the codes mean.
Lets start off with the whys.
The purpose of the Evaporative Emission system is to limit the amount of Hyrdocarbons released into the atsmosphere.
Fuel tank vapors are allowed to move from the fuel tank, due to pressure in the tank, through the vapor pipe, into the EVAP canister. Carbon in the canister absorbs and stores the fuel vapors. Excess pressure is vented through the vent line and EVAP vent solenoid to the atmosphere. The EVAP canister stores the fuel vapors until the engine is able to use them. At an appropriate time, the control module will command the EVAP purge solenoid ON, allowing engine vacuum to be applied to the EVAP canister. With the EVAP vent solenoid OFF, fresh air is drawn through the vent solenoid and the vent line to the EVAP canister. Fresh air is drawn through the canister, pulling fuel vapors from the carbon. The air/fuel vapor mixture continues through the EVAP purge pipe and EVAP purge solenoid into the intake manifold to be consumed during normal combustion. The control module uses several tests to determine if the EVAP system is leaking.
So in a nut shell if the control module senses a leak in the system that will allow more than a prescribed amount of fuel vapors escape, the module will illuminate the yellow engine light also know as the Check Engine (CEL)or Service Engine Soon (SES) light.
Depending on the year, make and model of your vehicle, this leak could be as small as .020” or twenty thousands of an inch ( a hole equal the point of a sharpened pencil lead)

Now with any diagnosis, the first thing we what to do after verifying the concern is to check the codes. This can be done at just about any chain auto parts store or if you own a code scanner, you can do it yourself.
DO NOT CLEAR THE CODE!!!!!!!!!!!!!!!!!!!! This is your key to finding out what is going on……we will clear the code after we repair the vehicle.

EVAP codes are considered either TYPE A or TYPE B codes..which in simple terms means the control module must see 1 failure for a TYPE A or 2 or more back to back failures for a TYPE B before the SES or CEL light is turned on.
Lets take a look at the codes and what they mean
P0440 or a P0455 – This is a Large leak indication or as people call it “The GAS CAP code”
This is a TYPE B code. Usually the code is caused by the gas cap being left off or loose after a refuel. This code could also be caused by any failure of the EVAP system that will cause a large leak.
P0442 – This is a Small leak indication.
This is a TYPE A code. This indicates a leak as small as .020”.
This code needs some serious diagnosis and knowledge of the system to find and repair the leak. Usually specialized equipment will be used to identify the leak.

P0446 – This indicates there is a restriction or blockage of the Vent Solenoid.
This is a TYPE B code. Any thing that prevents the venting of the EVAP system will set this code…usually dust and debris in the Vent solenoid or a damaged vent hose will cause this.

The other EVAP codes (P0443,449 etc) are electrical codes related to various components of the EVAP system.
Electrical codes need some good diagnostic skills, knowledge of the system and some specialized equipment.

With any car repair concern, there is a logical flow to follow when trying to identify what is going on..here in the GM world, we call it Strategy Based Diagnostics or 7 simple steps to diagnose a concern.
As always, verifying the concern and then doing a thorough visual inspection is key. It’s amazing how quickly a problem can be fixed by just the results of a visual inspection.
Now getting back to EVAP concerns….once you have identified the problem, you must come up with a repair, then a verification that the vehicle is repaired properly.
With EVAP leaks, usually a large leak is caused by a loose gas cap. Reinstalling the cap and clearing the code will be a quick remedy. But remember that you must always verify your repair..this could include professional intervention…(EEK!!!!!!!!!PAYING SOMEONE TO WORK ON MY CAR…..NO WAY!) . Well yes, this may be necessary..I have seen many times where people have come in to have a EVAP code cleared and refuse diagnosis only to have the light come back on…then blame me for the light coming back on…(then post on AF how the “stealership” did not fix their car).
But this isn’t a rant, this is information on what is going on.
Repair verification could include EVAP system testing with specialized equipment to verify that there are no leaks present..I personally check every EVAP system for leaks even if I find the customer left the gas cap loose…this insures that there are no other problems with the system that would cause the customer a trip back to see me. Far too many times have I seen someone tighten a gas cap and clear a code only to have the vehicle come back a few days later with a “real” EVAP leak…masked by a loose gas cap.
If you have a SES or CEL light caused by an EVAP concern and you have the code cleared and it comes back on after a few days….get to your local repair shop ( I recommend your local dealer with factory trained technicians) and have the system tested and repaired properly.
If you want to DIY the repairs, feel free, there are plenty of resources on the internet, but just don’t jump in and replace parts…educate yourself on the system and perform some diagnosis…many times a part will not fix the concern…
Good Luck
GMM