P0440
 

I can't figure out why my car throws this code every few weeks. Car runs exactly the same whether the light is on or off. I just have to plug in my scanner and clear the code. I've also replaced the gas cap, any other ideas on why this code keeps coming up every 3-4 weeks?

Something is not right with your emissions control system. This typically won't affect the performance of the engine, but can increase emissions. Here is a list of things to check. Unfortunately, tracking down the exact source can be a bit challenging.

Common Problems That Trigger the P0440 Code

• Missing fuel cap
• Defective or damaged fuel cap
• Distorted or damaged Fuel Tank Filler Neck
• Torn or punctured Evaporative system hose(s)
• Defective Fuel Tank Sending Unit gasket or seal
• Split or damaged Carbon Canister
• Defective Evaporative Vent Valve and/or Evaporative Purge Valve
• Defective or damaged fuel tank

Any suggestions or instructions on how to check/troubleshoot all those items on your list? So far only #1 has been replaced with a new gas cap...

from what I've seen, the second last item on that list is a relatively common failure mode. perhaps search this forum for 'evep' 'evaporative' or 'purge' to see if you can get some diagnosis and solutions.

Did you get your gas cap from the dealer?

Thanks for the tip. I'll look into it.

Yes, of course. I only use OEM for everything.

Is it bad to drive the car with this code?

Depends. Are you democrat or republican?

The code indicates a problem in the venting system of the fuel tank vapor recovery system.

If the fix isn't as simple as replacing the fuel cap, then there is a diagnostic process to determine exactly which component has failed.

This failure should not affect the drivability of the car and should not pose much risk of causing further damage. The car should be ok to drive until you can get it repaired.

My 2000 S has just begun to throw the code if I don't warm up the car to over 100 degrees before driving it. It has done it twice since the weather turned cold.

I replaced the gas cap and cleared the code. Drove about 50 miles and it stayed off.