P2003: Where does this line go?

chickenpie · 2026-09-05T14:22:20-0400

Hello all,

Im on the verge of finally getting my 2005 SLK 55 AMG registered and on the road. I've been battling an ESP module and possible EMI troubles for the past 3 weeks. I think i solved it but more on that in another post!

P2003 is the last thing keeping me from smogging this car. After troubleshooting some with Mr. Gemini, this plastic hose could be the culprit. Where is it supposed to go? It keeps telling me there is a 'nipple" that it inserts in, near the MAF, but I cannot see or feel anything... its currently going into the hose pictured, but that doesn't seem right...

Any help appreciated!

Electrical cable Wire Engine Fuel line Automotive Fuel System

Engine Automotive Fuel System Electrical cable Wire Fuel line

jbanks15 · 2026-09-05T16:45:18-0400

AI Overview

The circled tube appears to be a disconnected EVAP (evaporative emission) purge line or a small vacuum/breather hose attached to an emission solenoid component near the engine bay.

What it is

- Appears to be a rigid plastic or rubberized vacuum or vapor line associated with the EVAP system (evaporative emissions purge valve visible with the blue base below).
- It is currently unhooked or dangling near the cowl/firewall area.
What happens when it is disconnected
- - Vacuum leak: If it connects to manifold vacuum, you may notice a rough idle, higher idle speed, or engine stalling.
  - Check Engine Light: It will likely trigger an emissions-related diagnostic trouble code (like a P0441 or P0455 for EVAP flow).
  - Unmetered air: Can cause poor fuel economy or minor hesitation upon acceleration.

chickenpie · 2026-09-05T18:05:04-0400

I know what it is. I dont know where it goes. Ive talked to AI for an hour about it. There is no where it seems to go towards the back of the intake manifold like it statee

efair · 2026-09-05T20:22:41-0400

It goes back to the charcoal canister. There should be a hose heading that way.

chickenpie · 2026-09-06T17:18:21-0400

Do you have any pictures or references handy? I do not see any charcoal canisters in the engine bay (where this disconnected hose is found) or any disconnected lines. Perhaps it was removed or fell into the engine bay?

ccmano · 2026-09-06T16:24:12-0400

I'll bet you have a giant intake air leak with that hose disconnected. It goes into a rubber hose that connects directly into the back of the intake manifold. No doubt the source of your code and it must idle very poorly. It allows the engine it suck evap (gas) fumes so they can be burned in combustion. It's controlled by the solenoid on the other end of the plastic line you show. Where does the line you show it connected to go? Mine is slightly different because of the supercharger.
H

efair · 2026-09-06T16:32:34-0400

ccmano said:
I'll bet you have a giant intake air leak with that hose disconnected. It goes into a rubber hose that connects directly into the back of the intake manifold.

IIRC the manifold-facing port faces forward, which appears connected in the photo. So any leak would only occur during an EVAP purge cycle or during a leak test. And the ME can adapt the mixture for a leak such as this.

efair · 2026-09-06T20:29:38-0400

The charcoal canister is under the car, RHS, about in line with the fuel filler flap. I don't have access to EPC but a photo of the EVAP hoses might be helpful. Do you see any part numbers, Axxxxxxxxxx on any of these?

chickenpie · 2026-09-07T18:59:37-0400

I havent had the chance to look today, but i think i found some images from a general mercedes forum. It looks like that loose plastic hose needs to connect somewhere towards the front of the car, not the back. The cables from the secondary air pump seem to route around the passenger side. I was only looking at drivers side since AI was sure it connected the other way. Will try to look at it early evening.

Engine Automotive Fuel System Synthetic rubber

P2003: Where does this line go?

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