Bimmerfest BMW banner

1 - 13 of 13 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1
I've been trying to get my Z3 to an emissions test, but I've had a P0456 CEL for a while now. (P0456 = Very small EVAP leak)

I've replaced the gas cap, then replaced the purge valve and tightened the EVAP hoses in the hood, but it still returned after a while. The hard plastic tubing from the canister to the purge valve has an O-ring which seems a little worn out and loose. A replacement O-ring is already on the way.

There's also a slight gas smell from the rear, but only from outside the car. I'm wondering if this is related, or just normal exhaust.

Is there anything else I should check?

Thanks in advance, I appreciate any help.
 

·
BMW CCA 1405
1997 BMW Z3 1.9
Joined
·
5,134 Posts
... had a P0456 CEL for a while now. (P0456 = Very small EVAP leak)... also a slight gas smell from the rear, but only from outside the car. I'm wondering if this is related, or just normal exhaust...
Exhaust would not smell like gasoline. The gasoline you smell must be an evaporation leak. From the system, like from the canister, or the lines. Do you like to top off, override the pump, when filling the tank?
 

·
Registered
Joined
·
219 Posts
I would try to get someone to smoke test. Also you can usually avoid the code by keeping your car in between 1/4 full and 3/4 full. Usually the code is registered when all the way full or nearly empty. I would still try to fix it but this should allow you to pass the emissions.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #8
I would try to get someone to smoke test. Also you can usually avoid the code by keeping your car in between 1/4 full and 3/4 full. Usually the code is registered when all the way full or nearly empty. I would still try to fix it but this should allow you to pass the emissions.
That's a good idea, since I need to get it registered ASAP.

I replaced some hose clamps and o-rings today, and I'm wondering if the CEL will turn off by itself if the problem is fixed. Hoping to not have to clear CEL manually and then have to drive 30 miles again.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #9
Exhaust would not smell like gasoline. The gasoline you smell must be an evaporation leak. From the system, like from the canister, or the lines.
Could it still be a leak if there's no smell when the engine is not running? Could you guys point me to a DIY of inspecting the tank, canister, hoses etc? I've tried searching but haven't found any.

Thanks again.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #12
Also you can usually avoid the code by keeping your car in between 1/4 full and 3/4 full. Usually the code is registered when all the way full or nearly empty. I would still try to fix it but this should allow you to pass the emissions.
Thanks for this suggestion. I cleared the CEL, filled the tank and did the drive cycle. The result was everything ready and OK except for EVAP. Went through the smog test and passed.

In a few days we'll see if my fixes addressed the P0456 code.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #13
Update

I'm posting an update, for anyone who might have the same issue. The EVAP system has been ready for a few days now, and the CEL has not come back.

The cause seems to have been hoses and o-rings that have loosened over time. I removed, cleaned, replaced clamps and O-rings, and added RTV where needed throughout the EVAP line (but only under the hood, not under the car). I also replaced the EVAP Purge Valve just to be sure, since it's not too expensive.

Thank you, Vintage42 and zed3Coupe for your inputs.


(Of course right after this is fixed, a small rock hits the windshield and chips it. It never ends..)
 
1 - 13 of 13 Posts
Top