The other day I was replacing my thermostat housing for the second time. (It was done back in 2009.) It went pretty easy, 2 hours with beer. This morning I head to work and my Check Engine Light comes on. I happen to have a reader in my car at the time and it's throwing a P2400 code. As an easy try, I swung by the Stealership and got a gas cap. $22 later and I have a shinny new gas cap and still a P2400 CEL code. I cleared the code and the CEL goes out. As soon as I turn off the car and start it again, the CEL comes on and I've got a P2400 code.

I've searched this site and the internet, but can't find any real solutions for this. Anyone have any thoughts or experience with this?

Thanks in advance.

 

Anyone??

 

I found this:

P2400 - Evaporative Emission System Leak Detection Pump Control Circuit/Open

 

I found that as well, but does that mean the pump is bad? I'm thinking it means the pump is running, and that is why the CEL is on. But I'm not sure why?

 

The evap system includes the gas cap. That's the first thing to check.

The "pump control circuit/open" makes me think of an open circuit--something being unplugged. So that's another thing to check for.

 

Thanks for the input! I replaced the gas cap first thing. It was an easy fix, but no luck. I'll check to see if anything's unplug first thing in the morning.

 

Nothing appears to be unplugged, but feels like a needle in a hay stack. I found a thread on a bummer forum that talks about bleed down from a bad injector causing this code. Any thoughts on that? Do our injectors go bad often? Does anyone know a test to check for a bad injector? Thanks for the continued help!!

 

I can't see how an injector would affect the evaporative emissions control system.

In older cars, we had a charcoal filter in place to absorb gasoline fumes from the air that got into the tank as the gas emptied out of it. That filter vented into the intake for the engine, meaning any extra gas would just get burned up.

Nowadays, the system is more complex and works better at preventing evaporating fuel from getting out. The fuel system and such is sealed and air-tight, except for the air that gets in when you pump the fuel out. (And that is probably pretty strictly controlled as well!) There is a small pump that either pulls a slight vacuum on the system to make sure it is sealed, or puts a slightly pressure on the system, I don't know which. If the pressure changes from where the pump sets it, the system knows there is a leak.

It sounds like it has figured out that the pump isn't running at all.

Don't know where the pump is in our cars, though, nor exactly how it is controlled.

 

Thanks for the great info. I'll see if I can find it and trouble shoot it.

 

Did u ever solve this issue? i have the code now and theres alot of threads with no solutions. I have a leaky thermostat housing gasket and valve cover gasket, not sure if thats relevant.

 

Anyone have any input on this?

 

I had a bad wire to my pump.

 

Where was it bad? In the rear near the pump on the trailing arm like most others?

 

unfortunately I don't have the specifics the dealer did it for me, I changed the pump and the charcoal canister and finally the wire was the culprit.

 

I am going to fix mine tomorrow morning and take some detailed pictures for everyone

 

Bump - anyone else resolve this issue - if wire was bad, where was the wire bad?

Working on a 2010 R55 Clubman with N12 engine. Also throwing intermittent P0300 P0301-P0304 codes when cold.