SL/R230: Check Engine / Transmission
Thread Starter
Junior Member
Joined: Sep 2014
Posts: 53
Likes: 12
From: Indiana
2003 SL500 (70,000)
Check Engine / Transmission
Thanks to this forum, I've enjoyed 2 months and about 1200 miles of some of the most fun I've had in a car. I"m not a car guy, but trying to learn.
The other day when driving I noticed the car felt sluggish and I looked at the Tach and it was 3500 or so and would not shift into the highest gear. I slowed way down, tried to move it to manual and it stayed in D. When I accelerated again, still would not shift into high gear.
I pulled over, shut the car off - Re-started it and it was normal for the next few hundred miles.
Yesterday, it did it again. Again could not go into manual mode. (Reboot helped). Later, I did get a significant "bump" when shifting (in automatic) from 2-3 like getting tapped on the rear end. One time, no other issues.
It did it agin today, and also when driving in manual it wouldn't shift out of 2 and the Check Engine light came on.
Since owning this car, I did have my local mechanic do a transmission flush a month ago. I have not checked the fluid, I do not have a scan tool.
Can you point me to some possible things to explore. I'm taking it to the shop tomorrow - (it's about a 10 mile drive - should I tow it, or drive it?)
2003 SL 500 / 70,000 miles.
The other day when driving I noticed the car felt sluggish and I looked at the Tach and it was 3500 or so and would not shift into the highest gear. I slowed way down, tried to move it to manual and it stayed in D. When I accelerated again, still would not shift into high gear.
I pulled over, shut the car off - Re-started it and it was normal for the next few hundred miles.
Yesterday, it did it again. Again could not go into manual mode. (Reboot helped). Later, I did get a significant "bump" when shifting (in automatic) from 2-3 like getting tapped on the rear end. One time, no other issues.
It did it agin today, and also when driving in manual it wouldn't shift out of 2 and the Check Engine light came on.
Since owning this car, I did have my local mechanic do a transmission flush a month ago. I have not checked the fluid, I do not have a scan tool.
Can you point me to some possible things to explore. I'm taking it to the shop tomorrow - (it's about a 10 mile drive - should I tow it, or drive it?)
2003 SL 500 / 70,000 miles.
MBWorld Fanatic!
Joined: Aug 2020
Posts: 1,340
Likes: 366
From: Gretna, NE
'03 SL55 Black, '03 SL500's Aegean, Mars Red, Tazanite, Alabaster, '11 S550 Flint Gray
My first guess would be an accelerator pedal fault. This will cause a limp mode which will limit power and gear changes. I haven't tried to use manual mode in this limp mode, but it makes sense that it would be disabled. If it drive normal after a key cycle, I wouldn't have any issue driving it to the shop.
Thread Starter
Junior Member
Joined: Sep 2014
Posts: 53
Likes: 12
From: Indiana
2003 SL500 (70,000)
My first guess would be an accelerator pedal fault. This will cause a limp mode which will limit power and gear changes. I haven't tried to use manual mode in this limp mode, but it makes sense that it would be disabled. If it drive normal after a key cycle, I wouldn't have any issue driving it to the shop.
Thread Starter
Junior Member
Joined: Sep 2014
Posts: 53
Likes: 12
From: Indiana
2003 SL500 (70,000)
My first guess would be an accelerator pedal fault. This will cause a limp mode which will limit power and gear changes. I haven't tried to use manual mode in this limp mode, but it makes sense that it would be disabled. If it drive normal after a key cycle, I wouldn't have any issue driving it to the shop.
it drove completely normal the whole way there. The check engine light was on - I’m assuming it’s persistent once it’s activated until reset?
Senior Member
Joined: May 2020
Posts: 458
Likes: 55
From: North Carolina, USA
2004 SL500AMG, 2003 SL500 USA
I just found the accelerator problem, which is the TPS (Throttle Position Sensor) problem seriously caused my 7 speed to malfunction. I pressed the accelerator pedal and the rpms would only slightly increase. After a stop it might gain rpms more like normal intermittently. Before the TPS sensor symptoms were noticeable I had transmission problems occasionally limp mode. I occasionally left the negative battery cables disconnected overnight several times to enter transmission training mode. That kept me out of limp mode but i still had shifting problems. I just replaced the accelerator pedal assembly, and the tranny seems to be working well.
Last edited by aegea; Jun 17, 2024 at 10:20 PM.
Thread Starter
Junior Member
Joined: Sep 2014
Posts: 53
Likes: 12
From: Indiana
2003 SL500 (70,000)
I just found the accelerator problem, which is the TPS (Throttle Position Sensor) problem seriously caused my 7 speed to malfunction. I pressed the accelerator pedal and the rpms would only slightly increase. After a stop it might gain rpms more like normal intermittently. Before the TPS sensor symptoms were noticeable I had transmission problems occasionally limp mode. I occasionally left the negative battery cables disconnected overnight several times to enter transmission training mode. That kept me out of limp mode but i still had shifting problems. I just replaced the accelerator pedal assembly, and the tranny seems to be working well.
do you have a part number in case I end up down that road?
Last edited by TxBenzIn; Jun 17, 2024 at 11:20 PM.
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Senior Member
Joined: May 2020
Posts: 458
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From: North Carolina, USA
2004 SL500AMG, 2003 SL500 USA
Last edited by aegea; Jun 18, 2024 at 08:46 AM.
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Thread Starter
Junior Member
Joined: Sep 2014
Posts: 53
Likes: 12
From: Indiana
2003 SL500 (70,000)
My first guess would be an accelerator pedal fault. This will cause a limp mode which will limit power and gear changes. I haven't tried to use manual mode in this limp mode, but it makes sense that it would be disabled. If it drive normal after a key cycle, I wouldn't have any issue driving it to the shop.
https://www.fcpeuro.com/products/mer...e-1402700861oe
Good as New!
Thread Starter
Junior Member
Joined: Sep 2014
Posts: 53
Likes: 12
From: Indiana
2003 SL500 (70,000)
Banned
Joined: May 2023
Posts: 209
Likes: 3
just looking
Thanks to this forum, I've enjoyed 2 months and about 1200 miles of some of the most fun I've had in a car. I"m not a car guy, but trying to learn.
The other day when driving I noticed the car felt sluggish and I looked at the Tach and it was 3500 or so and would not shift into the highest gear. I slowed way down, tried to move it to manual and it stayed in D. When I accelerated again, still would not shift into high gear.
I pulled over, shut the car off - Re-started it and it was normal for the next few hundred miles.
Yesterday, it did it again. Again could not go into manual mode. (Reboot helped). Later, I did get a significant "bump" when shifting (in automatic) from 2-3 like getting tapped on the rear end. One time, no other issues.
It did it agin today, and also when driving in manual it wouldn't shift out of 2 and the Check notes ai Engine light came on.
Since owning this car, I did have my local mechanic do a transmission flush a month ago. I have not checked the fluid, I do not have a scan tool.
Can you point me to some possible things to explore. I'm taking it to the shop tomorrow - (it's about a 10 mile drive - should I tow it, or drive it?)
2003 SL 500 / 70,000 miles.
The other day when driving I noticed the car felt sluggish and I looked at the Tach and it was 3500 or so and would not shift into the highest gear. I slowed way down, tried to move it to manual and it stayed in D. When I accelerated again, still would not shift into high gear.
I pulled over, shut the car off - Re-started it and it was normal for the next few hundred miles.
Yesterday, it did it again. Again could not go into manual mode. (Reboot helped). Later, I did get a significant "bump" when shifting (in automatic) from 2-3 like getting tapped on the rear end. One time, no other issues.
It did it agin today, and also when driving in manual it wouldn't shift out of 2 and the Check notes ai Engine light came on.
Since owning this car, I did have my local mechanic do a transmission flush a month ago. I have not checked the fluid, I do not have a scan tool.
Can you point me to some possible things to explore. I'm taking it to the shop tomorrow - (it's about a 10 mile drive - should I tow it, or drive it?)
2003 SL 500 / 70,000 miles.
Super Member
Joined: Sep 2021
Posts: 546
Likes: 118
From: Ann Arbor, MI
2004 SL600
Your 2003 SL500 may be experiencing transmission issues, potentially related to low fluid levels, a malfunctioning transmission control module (TCM), shift solenoids, or an electrical problem. Given the symptoms and the Check Engine light, it's best to tow the car to the shop to avoid further damage. Have the transmission fluid checked and ensure the diagnostics are run to identify any error codes.
Senior Member
Joined: Dec 2019
Posts: 407
Likes: 137
From: Houston, TX
2005 SL600
@yovenim appears to be an AI bot. Or maybe a real person who gets a thrill out of posting AI generated responses to make themselves appear "smart". User post history shows dozens of the same kind of responses, posted in any/all of the various vehicle forums here.
As bad as the internet already is, this kind of AI garbage is going to make it even worse in the coming years. Loads of very well written, confident sounding, yet completely unhelpful answers to sift through in hopes of finding an actual knowledgeable response from a real human with experience.
As bad as the internet already is, this kind of AI garbage is going to make it even worse in the coming years. Loads of very well written, confident sounding, yet completely unhelpful answers to sift through in hopes of finding an actual knowledgeable response from a real human with experience.
Last edited by brucewane; Apr 29, 2025 at 12:39 PM.
Super Member
Joined: Sep 2018
Posts: 746
Likes: 185
From: Melbourne, Australia
2005 SL 500 R230
AI junk for sure. You can spot this turgid mess a mile off.
Loads of very well written.......
Except they're not; this junk is full of rotten syntax, random capitalisation, waffle and piffle. That's before the irrelevant and misleading answers.
I write for a living. If I turned in swill like this I would be sacked.
Loads of very well written.......
Except they're not; this junk is full of rotten syntax, random capitalisation, waffle and piffle. That's before the irrelevant and misleading answers.
I write for a living. If I turned in swill like this I would be sacked.
