Self-clearing ESP Malfunction + Intermittent Throttle Issues
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Junior Member
Joined: Mar 2023
Posts: 21
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From: USA
2003 C32 AMG Sedan
Self-clearing ESP Malfunction + Intermittent Throttle Issues
2003 C32 160k miles.
Replaced supercharger bearing. Car will run ok then suddenly ESP light on and power severely reduced.
New accel pedal + sensor (from this MBWorld thread ), did not fix. Battery is from Oct 2022– too old? Thought no, but idk.
Would check code but it keeps clearing itself so my scan tool can’t get ahold of it even in pending/etc.
Replaced supercharger bearing. Car will run ok then suddenly ESP light on and power severely reduced.
New accel pedal + sensor (from this MBWorld thread ), did not fix. Battery is from Oct 2022– too old? Thought no, but idk.
Would check code but it keeps clearing itself so my scan tool can’t get ahold of it even in pending/etc.
Thread Starter
Junior Member
Joined: Mar 2023
Posts: 21
Likes: 6
From: USA
2003 C32 AMG Sedan
update- Cleaned connections for throttle body, supercharger clutch. No fix. Scan tool unable to smell ESP codes (cheap Ancel scanner).
interesting- throttle position can go up to about 37.6% & car has full power when light-moderately depressed, BUT when flooring it I read a flat 33% and noticeable lack of power. Could this be throttle body?
edit: ordered throttle body, will send it back if it doesn’t help. found a new bosch unit online for $100; worth a try vs the $300 from Rock
interesting- throttle position can go up to about 37.6% & car has full power when light-moderately depressed, BUT when flooring it I read a flat 33% and noticeable lack of power. Could this be throttle body?
edit: ordered throttle body, will send it back if it doesn’t help. found a new bosch unit online for $100; worth a try vs the $300 from Rock
Last edited by MaxC32; Jul 27, 2023 at 11:40 AM.
Thread Starter
Junior Member
Joined: Mar 2023
Posts: 21
Likes: 6
From: USA
2003 C32 AMG Sedan
TB/Pedal No Help!
Updates— new battery. New throttle body. IAT reading approximately ambient up to 8° above ambient. Wheel speed readings match speedometer. Still, the problem persists. Noticed blasting off doesnt trigger it right away but rolling into WOT on a roll does.
side note— $100 throttle body was JUNK! If it seems too good to be true, it is, lol
side note— $100 throttle body was JUNK! If it seems too good to be true, it is, lol
Junior Member
Joined: Dec 2013
Posts: 42
Likes: 9
From: California/Hawaii
2003 C32 AMG
MaxC32 several questions.
1: Have you replaced the wheel speed sensor? This can cause the ESP issue or the ring the sensor reads?
2: Have you ever taken off the throttle body plug connector?
3: Have you checked your AIT?
The speed senor as mentioned can cause your ESP issue The sensor see a ring that spins as the wheel is rotating and it can become rusted and cause the sensor not to read the wheel rotating as well, the throttle body connector are known to fail after repeated removal and reconnection, a good product to use is Stabilant Electrical connection enhancer, You typically see the vehicle engine at idle hunting (rev up and down) but also see slow response to the accelerator pedal. The air intake temp AIT if exceeds 140F I believe will cut off the supercharger, this is caused by the liquid to air exchange system pump failing. check the supercharger coolant pump. if possible use a bluetooth ODBII that can scan the vehicle under load and read your AIT.
I have two 2003 C32's One almost 11 yrs now and have gone through a lot of the issues you are now experiencing I still have on my project C32 the ESP issue from time to time come up and have not addressed the issue as of yet, too Hot in central valley California to work on the vehicle and I can wait till fall to
hit the current issues I am having. Good luck sorting your issues out these are great vehicles and a wolf in sheep's clothing.
1: Have you replaced the wheel speed sensor? This can cause the ESP issue or the ring the sensor reads?
2: Have you ever taken off the throttle body plug connector?
3: Have you checked your AIT?
The speed senor as mentioned can cause your ESP issue The sensor see a ring that spins as the wheel is rotating and it can become rusted and cause the sensor not to read the wheel rotating as well, the throttle body connector are known to fail after repeated removal and reconnection, a good product to use is Stabilant Electrical connection enhancer, You typically see the vehicle engine at idle hunting (rev up and down) but also see slow response to the accelerator pedal. The air intake temp AIT if exceeds 140F I believe will cut off the supercharger, this is caused by the liquid to air exchange system pump failing. check the supercharger coolant pump. if possible use a bluetooth ODBII that can scan the vehicle under load and read your AIT.
I have two 2003 C32's One almost 11 yrs now and have gone through a lot of the issues you are now experiencing I still have on my project C32 the ESP issue from time to time come up and have not addressed the issue as of yet, too Hot in central valley California to work on the vehicle and I can wait till fall to
hit the current issues I am having. Good luck sorting your issues out these are great vehicles and a wolf in sheep's clothing.
Thread Starter
Junior Member
Joined: Mar 2023
Posts: 21
Likes: 6
From: USA
2003 C32 AMG Sedan
1. i have not! this is my first time hearing about this, thank you very very much for telling me about that.
2. yes, cleaned with MAF cleaner and re-attached (no stabilant on hand, elected not to use dielectric grease)
3. I read about ambient (89°F) or 4° F above. That seems good, but I don’t know a lick about the charge air cooling setup.
Funny enough, my last car (Honda) had a speed sensor & tone ring issue due to rust. I see a clean reading from the WSS on my reader but I understand these are sensitive systems. Worth a look!
Thank you very much for all the info
Thread Starter
Junior Member
Joined: Mar 2023
Posts: 21
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From: USA
2003 C32 AMG Sedan
Fixed fixed fixed
Brought car to a shop with proper scanner. They assessed that the supercharger clutch was not engaging properly, and re-shimmed it to get the gap within spec. It was fine after that!
Fortunately I didn’t drive it at all save for diagnosis during the period in which the clutch was malfunctioning, so hopefully it’s not too damaged from this experience.
Fortunately I didn’t drive it at all save for diagnosis during the period in which the clutch was malfunctioning, so hopefully it’s not too damaged from this experience.
