EVAP Code Came Back After Repairs - '05 325iT

[05325iT]

I had P0442 and lean codes, P0172/4 I think. Smoke test at mechanic shop revealed multiple vacuum leaks in intake boots, CCV system, and intake manifold. Replaced these parts, either BMW or OE. Did not replace intake gasket.

Replaced:

• Entire CCV System
• Dipstick O-Ring
• DISA O-Ring
• Purge/Breather Valve
• BMW Genuine Gas Cap

Cleaned:

• Throttle Body (did not move butterfly)
• Idle Control Valve

After doing these repairs, codes went away and car drove fine for about 300-400 miles. Car is running fine, no idle issues or performance issues from what I can tell. A few days ago I get a new P0440 code and what seems like bad gas mileage but still determining that.

The only thing I didn't repair was the Intake Manifold Gasket. Is that the likely cause of the new P0440 code? What else could be giving me a P0440 code but not performance issues?

[jclausen]

The fault has to do with the fuel vapor system evap system gas vapors from the tank are held in the car and not allowed to vent to the outside air. Every couple of drive cycles there is a pump in the evap system the dmtl pump and it self tests the system if the system does not hold the pressure and leaks the check engine light would come on, if the fault was say large leak the you might look for a missing or gas cap that has a bad seal for example a good fault reader beside displaying the fault will also list the type of fault it may be large leak small leak fine leak, purge valve ect. If nothing is obvious then smoke checking the purge valve line in the engine compartment goes back to the dmtl pump and other parts and it is located behind the passenger rear wheel well cover. Most of the time the car will run ok with these faults

[05325iT]

I replaced almost the entire EVAP system which got rid of the P0442 and P1072/4 codes, but now I'm getting a P0440 code. So besides the intake manifold gasket, you're suggesting checking the DMTL pump as the other culprit?

[dworthy]

Yes, and I would see about going back to check your work, for if a clamp isn't all the way tight, that too can cause a small leak in the system.

[05325iT]

Sure that's a possibility. But first I was trying to determine what other parts of the EVAP system could be causing the code before I got back and redo the work. Also the codes are different. First, I got a P0442 and P1072/4 codes which are more specific than the generic P0440 code which makes me think that i's a different issue unrelated to the work I just did, ie. intake manifold gasket which wasn't replaced.

[easymoney]

How about your gas cap? Try using another one.

[05325iT]

I already replaced the gas cap with a brand new BMW one.

[dworthy]

Then can you get the system smoke tested? That would be the easiest way to find any leak that it may have.

[05325iT]

The car was smoke tested and there were leaks coming from the CCV system as well as under the intake manifold. I'm assuming the P0440 code is from the intake manifold gasket leak, but before I disassemble half the engine to replace it, I wanted to make sure there wasn't another part of the EVAP system that could be causing it because the codes present during the smoke test (P0442 and P1072/4) are gone and now a new code, P0440 has appeared.

I could be wrong, but I would assume that if the Intake Manifold was leaking, I would've also been getting the P0440 code along with the others. I understand P0440 is a generic EVAP code, but it's odd that it wasn't present pre-repair when I was getting the other EVAP codes.

Timeline:
• P0442 and P1072/4 Codes are present
• Smoke Test reveals leaks in CCV, intake boots, and Intake Manifold
• Replace the parts listed above (CCV, Purge Valve, intake boots etc) but intake gasket is NOT replaced.
• Codes are gone and have not come back after 400+ miles
• New P0440 code comes on.

[dworthy]

You should always get another smoke test after repairs are completed, this just rules out smaller holes that may have been missed the first time.

The evap system has a one way check vavle, so you will not get smoke into there from the intake, it will have to be tested separately from the intake.

[jclausen]

I believe po440 is an evap related fault after repairs cLear faults and see what happens if 440 comes back remove right rear wheel and the liner so when you smoke test the evap system say though the purge valve line and you will see if any thing leaks back there

[dzlockhead]

I may have missed it if you did this, but I really recommend replacing the DMTL pump. I had evap codes, and this was the first thing I did after I had a mechanic smoke test the car and they said they found nothing. Instant fix, never had the issue come back after it.

[Muzz258]

If it is the purge valve, I would buy a new/used genuine BMW evap purge valve before buying any new off-brand ones. The DME is very sensitive to the voltage drop across the evap solenoid.