SL/R129: Rough Idle, P0442, Center Vents don't work, interior intermittently smells like exhau
Thread Starter
Senior Member
Joined: Mar 2020
Posts: 253
Likes: 46
From: Riverside, CA
1999 SL600
Rough Idle, P0442, Center Vents don't work, interior intermittently smells like exhau
1999 SL600.
Anyone go thru these strange combo of issues in the title?
The engine light is on and the only code I get is P0442 after repeat code clears in STAR.
Right (yes there's 2 of them on the v12) purge valve has been replaced and the vacuum hosing that's visible to it from the charcoal canister looks fine. Same with the exit vacuum hose going to the right throttle body. My engine bay vacuum block connections are fine. Engine bay smells like exhaust too, and supposedly I have an exhaust leak at left exhaust manifold but not sure if it plays a role in the grand scheme of things.
Documentation says these are the possible causes of P0442:
ChatGPT suggests that given the rough idle and the code, its either Purge Lines to and from the Charcoal Canister or the charcoal canister shutoff valve pn# 000-476-69-32.
What do you guys think? Gas cap obviously was checked and its not old. Has anyone ever had to replace their charcoal canister shutoff valve?
Anyone go thru these strange combo of issues in the title?
The engine light is on and the only code I get is P0442 after repeat code clears in STAR.
Right (yes there's 2 of them on the v12) purge valve has been replaced and the vacuum hosing that's visible to it from the charcoal canister looks fine. Same with the exit vacuum hose going to the right throttle body. My engine bay vacuum block connections are fine. Engine bay smells like exhaust too, and supposedly I have an exhaust leak at left exhaust manifold but not sure if it plays a role in the grand scheme of things.
Documentation says these are the possible causes of P0442:
- Fuel tank cap
- Purge line to charcoal canister
- Purge line from charcoal canister to Y58/4 (activated charcoal canister shut-off valve)
- Activated charcoal canister
- Y58/4 (activated charcoal canister shut-off valve)
- Fuel tank pressure sensor (B4/3)
ChatGPT suggests that given the rough idle and the code, its either Purge Lines to and from the Charcoal Canister or the charcoal canister shutoff valve pn# 000-476-69-32.
What do you guys think? Gas cap obviously was checked and its not old. Has anyone ever had to replace their charcoal canister shutoff valve?
Senior Member
Joined: Oct 2017
Posts: 368
Likes: 73
SL600
What is always broken, if no one replaced it in the past, is one of the vacuum at the charcoal canister. Gasoline eats rubber, take a clother look. Another classic failure is a leaky fuelpressure regulator. This causes petrol to drip from the side vacuum hose, dissolve the rubber vacuum line and petrol is dripping onto the engine.
One line leads from the vacuum canister to a T-fitting under the brake booster. From there, a line leads to each of the two purge valves. If you pull on the hoses too hard and pull them out of the T-fitting, you have a problem: you will never be able to get to it again to reconnect it. Then the only thing that helps is to lay a new line from the activated charcoal canister to one of the two valves and close the other one.
One line leads from the vacuum canister to a T-fitting under the brake booster. From there, a line leads to each of the two purge valves. If you pull on the hoses too hard and pull them out of the T-fitting, you have a problem: you will never be able to get to it again to reconnect it. Then the only thing that helps is to lay a new line from the activated charcoal canister to one of the two valves and close the other one.
Thread Starter
Senior Member
Joined: Mar 2020
Posts: 253
Likes: 46
From: Riverside, CA
1999 SL600
What is always broken, if no one replaced it in the past, is one of the vacuum at the charcoal canister. Gasoline eats rubber, take a clother look. Another classic failure is a leaky fuelpressure regulator. This causes petrol to drip from the side vacuum hose, dissolve the rubber vacuum line and petrol is dripping onto the engine.
One line leads from the vacuum canister to a T-fitting under the brake booster. From there, a line leads to each of the two purge valves. If you pull on the hoses too hard and pull them out of the T-fitting, you have a problem: you will never be able to get to it again to reconnect it. Then the only thing that helps is to lay a new line from the activated charcoal canister to one of the two valves and close the other one.
One line leads from the vacuum canister to a T-fitting under the brake booster. From there, a line leads to each of the two purge valves. If you pull on the hoses too hard and pull them out of the T-fitting, you have a problem: you will never be able to get to it again to reconnect it. Then the only thing that helps is to lay a new line from the activated charcoal canister to one of the two valves and close the other one.
And I already replaced the fuel pressure regulator along with all 4 o2 sensors as initially the code 442 small evap leak was also paired with 455 large evap leak and 170 right bank fuel trim. P0455 and P0170 haven't retuned for whatever reason.
