SL55/63/65/R230 AMG: YIKES - Fuel pressure is 110 PSI
Thread Starter
Super Member
Joined: Sep 2021
Posts: 537
Likes: 116
From: Ann Arbor, MI
2004 SL600
YIKES - Fuel pressure is 110 PSI
After noticing that my LTFT (Long Term Fuel Trims) were maxed out at -20%, I checked the fuel pressure on the injector rail and it reads 110PSI, nearly double what it should.
It seems that the different R230 engines regulate fuel pressure in different ways. I believe that the SL600 and SL65 are the same. This car was originally an SL600, now with an SL65 AMG engine.
(The M275 Global Training manual shows a fuel pressure sensor right after the 4-port fuel filter.)
I expected to see a regulator near the fuel pump/filter, but there is none; there is only a control box with part number A 230-540-48-45 which connects to the fuel pump. While I have spares of many/most control modules, I don't have this one and it is over $350 new.
Unless I'm blind, there is no fuel pressure sensor on the engine's fuel rail.
Is a fuel pressure sensor hiding somewhere else?
I see a supposed fuel pressure sensor #A4639053400 listed for 2005 SL65 and SL600. Is this it? Is it hiding somewhere between the rear and front of the car?
Thank you for reading.
BTW - I proactively replaced the fuel pump and filter a year ago when I still had the SL600 engine. Car ran fine, but I never checked the LTFT nor fuel rail pressure.
BTW2 - I recently completed swapping the SL600 engine for the AMG engine from a CL65. I'm working on a detailed writeup; not a trivial swap, partly due to CL65 and SL65 differences, ECU swap issues, crazy ABC problems, etc.
It seems that the different R230 engines regulate fuel pressure in different ways. I believe that the SL600 and SL65 are the same. This car was originally an SL600, now with an SL65 AMG engine.
(The M275 Global Training manual shows a fuel pressure sensor right after the 4-port fuel filter.)
I expected to see a regulator near the fuel pump/filter, but there is none; there is only a control box with part number A 230-540-48-45 which connects to the fuel pump. While I have spares of many/most control modules, I don't have this one and it is over $350 new.
Unless I'm blind, there is no fuel pressure sensor on the engine's fuel rail.
Is a fuel pressure sensor hiding somewhere else?
I see a supposed fuel pressure sensor #A4639053400 listed for 2005 SL65 and SL600. Is this it? Is it hiding somewhere between the rear and front of the car?
Thank you for reading.
BTW - I proactively replaced the fuel pump and filter a year ago when I still had the SL600 engine. Car ran fine, but I never checked the LTFT nor fuel rail pressure.
BTW2 - I recently completed swapping the SL600 engine for the AMG engine from a CL65. I'm working on a detailed writeup; not a trivial swap, partly due to CL65 and SL65 differences, ECU swap issues, crazy ABC problems, etc.
Thread Starter
Super Member
Joined: Sep 2021
Posts: 537
Likes: 116
From: Ann Arbor, MI
2004 SL600
As a quick update, I did find the fuel pressure sensor; I only had to remove one rear heat shield by the axle. The MB "EPC" system shows this as part # A003-542-48-18. I ordered a A463-905-34-00 which I now hope is an updated part #.
I will update this thread once I get the new sensor and confirm whether it fixes my high fuel pressure.
I will update this thread once I get the new sensor and confirm whether it fixes my high fuel pressure.
Thread Starter
Super Member
Joined: Sep 2021
Posts: 537
Likes: 116
From: Ann Arbor, MI
2004 SL600
I installed the new fuel pressure sensor today and now have the correct 56 psi at idle.
I ordered the A463-905-34-00 from AutoHausAZ at a price of $240. I need not need their recommended extra cable; it fact it did not work with it as it flips the wires around; it must be for a different MB.
I ordered the A463-905-34-00 from AutoHausAZ at a price of $240. I need not need their recommended extra cable; it fact it did not work with it as it flips the wires around; it must be for a different MB.
