S55 AMG (2005) secondary coolant pump.
Thread Starter
Newbie
Joined: Dec 2023
Posts: 5
Likes: 3
S55 AMG
S55 AMG (2005) secondary coolant pump.
Hi all.
I am working on an S55 AMG that has a P202C:8 (P0128) code for thermostat performance.
the thermostat was replaced a few months ago but the code came back.
I ran a warmup cycle from cold and it warmed up fine and within time. So I recommended replacing the thermostat and coolant temp sensor.
when I was replacing the coolant temp I found frayed wires going to it so I suspect this was the issue as they were probably shorting intermittently.
anyways, did belts and pulleys as well and refilled the coolant. During the bleeding process I connected a clear hose from the upper kompressor coolant line and back into the coolant reservoir to watch for bubbles but there was no flow with the engine running.
I tried lookin for repair info about the secondary coolant pump for the kompressor and other than the relay that runs it I found no info.
I assume there is some sort of circuit controlling the pump but I can't find info
about it. My scan tool (Autel 919) which can do a lot of the MB tests and see live data, does not have a test for it unless I missed it.
so my question is,
where can I find info about the pump and when it should run so i can trouble shoot it?
I am working on an S55 AMG that has a P202C:8 (P0128) code for thermostat performance.
the thermostat was replaced a few months ago but the code came back.
I ran a warmup cycle from cold and it warmed up fine and within time. So I recommended replacing the thermostat and coolant temp sensor.
when I was replacing the coolant temp I found frayed wires going to it so I suspect this was the issue as they were probably shorting intermittently.
anyways, did belts and pulleys as well and refilled the coolant. During the bleeding process I connected a clear hose from the upper kompressor coolant line and back into the coolant reservoir to watch for bubbles but there was no flow with the engine running.
I tried lookin for repair info about the secondary coolant pump for the kompressor and other than the relay that runs it I found no info.
I assume there is some sort of circuit controlling the pump but I can't find info
about it. My scan tool (Autel 919) which can do a lot of the MB tests and see live data, does not have a test for it unless I missed it.
so my question is,
where can I find info about the pump and when it should run so i can trouble shoot it?
MBWorld Fanatic!
Joined: Feb 2012
Posts: 2,617
Likes: 1,214
From: Phoenix
222 S-65
There is a relay that powers up charge cooling. Many jump power supply to output on that relay such that the charge cooling pump runs anytime the engine runs. There are many threads on charge cooling. Add another heat exchanger for charge coolant and upsize the charge cooling pump. Lower charge temps are your friend.
Use the search function on this board. Set aside an afternoon to read all about it.
Use the search function on this board. Set aside an afternoon to read all about it.
Member
Joined: Sep 2021
Posts: 125
Likes: 27
2004 e500
Upgrade to the Bosch 010 pump and you shouldn't have intake temp issues with stock setup. Also, S55 have a hose permanently attached from the bleed pipe to the coolant tank.
You can also get the FCP BMW split cooling system.
You can also get the FCP BMW split cooling system.
Thread Starter
Newbie
Joined: Dec 2023
Posts: 5
Likes: 3
S55 AMG
do you know what triggers the pump? What temps?
