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I bought a $1500 Autel (MS906 Pro) and have been exploring various coding options on my 2013 G63. Here are my initial findings, sharing for anyone else interested. I am barely scratching the surface so if folks know of other coding options, please post and I can verify with tablet.
Axle ratio can be adjusted in the VG (transfer case) module. If you upsize your tires to 33"/34" it is useful to recode the software axle ratio to get the transmission shift schedules back to normal (they get lazy with big tires).
Lockers can be coded to engage in High.
Headlight zero point location can be recalibrated (useful after lift)
Throttle pedal maps can be adjusted
TPMS module can be restarted/reprogrammed
There are some Instrument Cluster options like auto high beams that can be activated.
Wheel/tire circumference CANNOT be changed unfortunately. It does not show up under the IC or ESP modules for my model year. Bummer.
Last edited by xxaarraa; Apr 10, 2026 at 07:15 AM.
Interesting -- I attempted to change my tire circumference using a Launch OBD scanner. There were several options, but none of them produced any change. There must be a way to do this, but must require MB's SDS.
I bought a $1500 Autel (MS906 Pro) and have been exploring various coding options on my 2013 G63. Here are my initial findings, sharing for anyone else interested. I am barely scratching the surface so if folks know of other coding options, please post and I can verify with tablet.
Axle ratio can be adjusted in the VG (transfer case) module. If you upsize your tires to 33"/34" it is useful to recode the software axle ratio to get the transmission shift schedules back to normal (they get lazy with big tires).
Lockers can be coded to engage in High.
Headlight zero point location can be recalibrated (useful after lift)
Wheel/tire circumference CANNOT be changed unfortunately. It does not show up under the IC or ESP modules for my model year. Bummer.
IF these work in actual application, it would be very useful for lifted G's. The tighter shift points would be great and there's a lot of utility in using lockers in 4H. I would (foolishly?) think that if you made it believe it had a new gear ratio, that it would also effectively recalibrate the speedometer to some degree based on tire size.
I have driven about 150 miles since recoding and it’s an DEFINITE improvement. Here are my observations:
Under moderate throttle from standstill, gears are held MUCH longer. I see transmission shifting closer to 3k-3.5k now when in the past it would shift well under 2k. With peak torque being 2k rpm, this alone keeps it from falling out of power band during upshifts. This is a result of recoding axle ratio in three places (details below).
Downshifts while slowing seem more assertive.
30-60 mile steady coasting on back roads or city streets, car seems to have more torque on hand and doesn’t go to sleep like it used to in 7th gear.
Overall, car seems more eager/lively/playful while it was grumpy before. I suspect this has a lot to do with the throttle map change.
No change to mpg. In fact there may be a slight improvement.
I cannot find a way to change tire size anywhere. So speedo is still off unfortunately (6%).
Here’s a summary of everything I recoded. This is my best estimate based on research for correct settings after lift and 33” tires.
Lockers enabled for high range (VG module) Not related to lift, just a convenience.
Rear axle ratio set to 4.375 (VG module)
Rear axle ratio set to 4.375 (ESP module)
Rear axle ratio set to 3.9 (ECM module). More on why this is different below.
Accelerator pedal characteristic curve set to KLD_1_2 (ECM module) Two levels more aggressive from stock.
Reset headlight zero point value (Body under ECM)
Limitation of engine torque parameter set 2 set to torque limiting 2 (ECM module)
NCV weight class set to Middle (ECM module)
That is correct, rear axle ratio is in three different modules. Tcase (VG) and ESP must match but ECM does not. They all have different available values and used for different purposes. Axle ratio changes to VG affect shift schedules, axle ratio changes to ESP affect stability and traction control and axle ratio changes to ECM affect torque output and torque cuts during gear shifts. None of them have to match mechanical ratio in the diff (which is 4.1). These values are used by the modules for calculations and increasing them tricks the modules into correcting for negative effects introduced by big tires.
#7 and #8 above were incorrectly coded in my car. 6 should be on for all AMG models and 7 should not be ‘light duty’ for G wagon. I do not know if it was incorrect from factory or if it was over written incorrectly at some point (I did have a eurocharged ecu tune for a bit then reverted back to stock).
Anyone with a lift and big tires must recode! Big difference!
Last edited by xxaarraa; Apr 11, 2026 at 06:15 PM.
Wonder if I have any of these options also. Will look when I get my system back in a few weeks. I would definitely want to be able to engage the lockers in H. When my fix my transfer case issue.
Wonder if I have any of these options also. Will look when I get my system back in a few weeks. I would definitely want to be able to engage the lockers in H. When my fix my transfer case issue.
I'd love to know how much of actual STAR functionality my cheater tablet allows. Keep us posted.
Also, I thought you fixed your tcase when you had the car in for major work including rebuilding the front grease *****.
Ordered it to try out the One-Click coding options - not as in depth as Autel, or Xentry, but want to code auto start/stop off, and turn seat belt chimes off
Ordered it to try out the One-Click coding options - not as in depth as Autel, or Xentry, but want to code auto start/stop off, and turn seat belt chimes off
I have driven about 150 miles since recoding and it’s an DEFINITE improvement. Here are my observations:
Under moderate throttle from standstill, gears are held MUCH longer. I see transmission shifting closer to 3k-3.5k now when in the past it would shift well under 2k. With peak torque being 2k rpm, this alone keeps it from falling out of power band during upshifts. This is a result of recoding axle ratio in three places (details below).
Downshifts while slowing seem more assertive.
30-60 mile steady coasting on back roads or city streets, car seems to have more torque on hand and doesn’t go to sleep like it used to in 7th gear.
Overall, car seems more eager/lively/playful while it was grumpy before. I suspect this has a lot to do with the throttle map change.
No change to mpg. In fact there may be a slight improvement.
I cannot find a way to change tire size anywhere. So speedo is still off unfortunately (6%).
Here’s a summary of everything I recoded. This is my best estimate based on research for correct settings after lift and 33” tires.
Lockers enabled for high range (VG module) Not related to lift, just a convenience.
Rear axle ratio set to 4.375 (VG module)
Rear axle ratio set to 4.375 (ESP module)
Rear axle ratio set to 3.9 (ECM module). More on why this is different below.
Accelerator pedal characteristic curve set to KLD_1_2 (ECM module) Two levels more aggressive from stock.
Reset headlight zero point value (Body under ECM)
Limitation of engine torque parameter set 2 set to torque limiting 2 (ECM module)
NCV weight class set to Middle (ECM module)
That is correct, rear axle ratio is in three different modules. Tcase (VG) and ESP must match but ECM does not. They all have different available values and used for different purposes. Axle ratio changes to VG affect shift schedules, axle ratio changes to ESP affect stability and traction control and axle ratio changes to ECM affect torque output and torque cuts during gear shifts. None of them have to match mechanical ratio in the diff (which is 4.1). These values are used by the modules for calculations and increasing them tricks the modules into correcting for negative effects introduced by big tires.
#7 and #8 above were incorrectly coded in my car. 6 should be on for all AMG models and 7 should not be ‘light duty’ for G wagon. I do not know if it was incorrect from factory or if it was over written incorrectly at some point (I did have a eurocharged ecu tune for a bit then reverted back to stock).
Anyone with a lift and big tires must recode! Big difference!
Quick question for you, what is the logic behind the 3.9 that you put in the ESP section ? You explained that you CAN do it, but now WHY ? I'm curious. I have a 2018 and the highest gear ratio available in the ESP was 3.7 in my case.
Ordered it to try out the One-Click coding options - not as in depth as Autel, or Xentry, but want to code auto start/stop off, and turn seat belt chimes off
Quick question for you, what is the logic behind the 3.9 that you put in the ESP section ? You explained that you CAN do it, but now WHY ? I'm curious. I have a 2018 and the highest gear ratio available in the ESP was 3.7 in my case.
Correction - ESP and VG are set to 4.375. ECM is set to 3.9. In any of those modules, you pick from the drop down and 3.9 was the highest in ECM before it jumped to 5.2. Here is the explanation for why I updated:
(from Copilot)
The ECM “rear axle reduction ratio” is not a real axle ratio. Inside the ECM, that field is a torque‑model category, not a mechanical value.It adjusts:
2. 3.9 is the correct torque‑model family for a G63 running 33” tires. The 3.9 category:
• reduces calculated wheel torque by the correct amount • keeps load estimation inside the expected envelope • prevents over‑correction of throttle and boost • keeps TCM shift logic stable • avoids ESP torque‑intervention errors
Your move from 31” → 33” tires increases effective gearing by ~6–7%. Mercedes compensates this through ECM torque‑model categories, not by matching the VG ratio.
It means OBDeleven is now officially approved/licensed by Mercedes-Benz, so it’s not just regular OBD2 support. They have licensed access to Mercedes systems/coding, which should make the diagnostics and features more legitimate and reliable
It means OBDeleven is now officially approved/licensed by Mercedes-Benz, so it’s not just regular OBD2 support. They have licensed access to Mercedes systems/coding, which should make the diagnostics and features more legitimate and reliable
Is this posted somewhere on the OBDeleven website?
Correction - ESP and VG are set to 4.375. ECM is set to 3.9. In any of those modules, you pick from the drop down and 3.9 was the highest in ECM before it jumped to 5.2. Here is the explanation for why I updated:
(from Copilot)
The ECM “rear axle reduction ratio” is not a real axle ratio. Inside the ECM, that field is a torque‑model category, not a mechanical value.It adjusts:
2. 3.9 is the correct torque‑model family for a G63 running 33” tires. The 3.9 category:
• reduces calculated wheel torque by the correct amount • keeps load estimation inside the expected envelope • prevents over‑correction of throttle and boost • keeps TCM shift logic stable • avoids ESP torque‑intervention errors
Your move from 31” → 33” tires increases effective gearing by ~6–7%. Mercedes compensates this through ECM torque‑model categories, not by matching the VG ratio.
I've been running 275/55R20s in place of the OE 275/50R20s for 6 years and 26K miles. The only consequence is a 3% error in the speedo and odo. I tried to find a coding sequence using the Launch scanner, but the couple attempts produced no change. I think XEntry can re-code tire circumference, but I'm not aware of any OBD scanner that can. I'm due new tires (due to tire age) later this year, and I'm planning to mount Michelin CC2s in the OE 275/50R20 size.
@streborx All that coding tire circumference does is change/adjust/correct speedo and it is done in the IC module. Coding changes to ECM/ESP and VG modules change how the car behaves and most importantly how the transmission shifts. Much more important than speedo correction.
Originally Posted by scyan
Do you happen to have screenshots of the modules where you made the changes ? We had issues finding where to make them.
What scanner are you using? They might all have different UIs and different screens. Here are the photos from Autel MS906 Pro - the breadcrumbs in blue font at top show you which module and which menu.
Yes, I know that. Why would I mess with other parameters, important or not, to correct speedo/odo error?
To get shift schedules back to normal. Bigger tires change effective gear ratio and make the truck lazy. G is extremely sensitive to changes in effective gear ratio because of all the computerized modules using the gear ratio calculation.
If I run a 275/55-20 vs the stock 275/50-20, do you recommend doing any code changes?
Your change is roughly 3.5% increase in wheel circumference. That is not much. Two suggested questions for you - what is the relative weight of the tires you went to, compared to stock and did you lift the truck or are you at stock height?
Going to bigger tires changes effective gear ratio. Going to heavier tires changes rotational inertia and indirectly contributes to truck feeling lazy with stock gearing.
Lifting the g increases drag like mad, and again, indirectly contributes to truck feeling lazy with stock gearing.
Ultimately, if you have driven it for 26k miles and your butt dyno hasn't told you anything is off, you are probably fine. Different butt dynos are tuned differently, mine unfortunately is extremely sensitive.
Your change is roughly 3.5% increase in wheel circumference. That is not much. Two suggested questions for you - what is the relative weight of the tires you went to, compared to stock and did you lift the truck or are you at stock height?
Going to bigger tires changes effective gear ratio. Going to heavier tires changes rotational inertia and indirectly contributes to truck feeling lazy with stock gearing.
Lifting the g increases drag like mad, and again, indirectly contributes to truck feeling lazy with stock gearing.
Ultimately, if you have driven it for 26k miles and your butt dyno hasn't told you anything is off, you are probably fine. Different butt dynos are tuned differently, mine unfortunately is extremely sensitive.
No lift. Went with Pirelli Scorpion Verde for mild weather and run 285/55-20 Blizzaks for winter. Since I put the new 275/55-20 Pirellis on as soon as I purchased it, I have no comparison to the stock 275/50s. Really just curious.
I went with 275/55R20's not out of a cosmetic urge, but only because choices in AT/3MPSF all weather tires were slim 6 years ago. I drive it only about 4K/year, which doesn't justify swapping tires seasonally The Yokohama Geolandar 015's I installed have been fine even with being 3% larger. I've kept the truck stock except for the tires and a couple of minor cosmetic changes (and disabling LKA and auto S/S, both which made the truck annoying and nearly un-driveable). CC2s are available in 275/50R20, while the Yokohama X-AT (successor to the 015) has only 275/55R20. I have all summer to decide -- as I said, it's not a treadwear issue but instead that the 015's are 6 years old.
@streborx All that coding tire circumference does is change/adjust/correct speedo and it is done in the IC module. Coding changes to ECM/ESP and VG modules change how the car behaves and most importantly how the transmission shifts. Much more important than speedo correction.
What scanner are you using? They might all have different UIs and different screens. Here are the photos from Autel MS906 Pro - the breadcrumbs in blue font at top show you which module and which menu.
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