Modified E6 torx socket for removing ESP module on FL R170

LAZARU5 · 2026-09-01T12:23:17-0400

Based upon my diagnostics efforts (coached by ChatGPT) I am fairly confident that the ESP module in my 2004 SLK320 needs to be replaced. I ordered a used ABS/ESP assembly (170-545-01-32) from an eBay seller. While waiting for it to arrive I modified an E6 torx socket to facilitate removal of the ESP module.

First picture shows an unmodified E5 socket along with the modified E6 socket. I used a mill file to make the 10mm hex on the drive end of the socket. The hex is slightly larger than a standard M6 10mm hex nut so that the socket fits snuggly into a 10mm Gearwrench.

I confirmed that I could break the E6 screws loose with the socket on the upper and lower screws securing the ESP module. I am hoping that I do not need more than about 16mm of clearance between the module and the fuse box to exctract the ESP module. I will remove the module from the donor assembly first to determine whether or not I have to remove the installed assembly from the rubber mounts on the wheel well.

Once I successfully complete this project I will summarize the diagnostics process I used and the steps I took to replace the ESP module.

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slk230red · 2026-09-01T14:49:38-0400

I removed the fuse box surround and it gave me a bit more clearance.

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LAZARU5 · 2026-09-01T15:35:20-0400

I appreciate that tip.

slk230red · 2026-09-02T08:57:04-0400

As I recall, I had to pull the pump forward just enough to pull out the module. Glad it's installed on those rubber bushings.

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LAZARU5 · 2026-09-02T10:19:14-0400

slk230red said:
As I recall, I had to pull the pump forward just enough to pull out the module. Glad it's installed on those rubber bushings.

Are you saying you were able to just nudge the block over without pulling the assembly out of the rubber bushings. I noticed there is an extra 3mm of clearance on the outboard side.

slk230red · 2026-09-02T11:06:27-0400

Yes, just enough to remove the module.
Is the 320 module thicker than the 230 module?

M4rCu5 · 2026-09-02T12:38:47-0400

slk230red said:
Yes, just enough to remove the module.
Is the 320 module thicker than the 230 module?

320 and the '32 come out same as you have said Red

LAZARU5 · 2026-09-03T17:11:00-0400

I attempted to remove the ESP module today without removing the mounting bracket from the rubber grommets in the wheel well. I was able to get the module to clear the ~22mm long solenoid posts but I just could not get the 33mm long pump power post by the rear most brake line attached to the top of the aluminum block. I am going to try again tomorrow after pulling the mounting bracket pins away from the rubber grommets.

Picture of pump power post on donor ESP module.

JackMeyers · 2026-09-04T09:31:38-0400

LAZARU5 said:
I attempted to remove the ESP module today without removing the mounting bracket from the rubber grommets in the wheel well. I was able to get the module to clear the ~22mm long solenoid posts but I just could not get the 33mm long pump power post by the rear most brake line attached to the top of the aluminum block. I am going to try again tomorrow after pulling the mounting bracket pins away from the rubber grommets.

Picture of pump power post on donor ESP module.

That rear brake line is usually the bit that makes it feel like it “almost” comes out but not quite. Pulling the bracket pins out of the rubber grommets should give you the extra wiggle room you need, just go gently so you’re not stressing the hard lines.

If you can, support the pump/block as you move it and avoid levering against the aluminium valve body. A little silicone spray on the rubber grommets can help the pins slide back in afterwards. Take a couple of photos of the angle that finally works too — that’ll be useful for the next person fighting the same clearance issue.

LAZARU5 · 2026-09-04T12:10:02-0400

I removed the front wheel and made a jacking post from a 2x6 with two M8 cap screws placed into 8mm holes about 90mm apart. I sprayed the rubber mounts from inside the fender well with WD40 Specialist Silicone and lifted the two rear bracket pins. I unclipped the brake line near the ground connection on the wheel well. Since I only raised the rear two bracket pins the forward most pin did not move as far and the ABS/ESP assembly tilted slightly forward.

After pushing the pins upward the gap between the rear brake line on top of the aluminum block and the edge of the fuse box with rim removed increased from ~60mm to ~80mm. This was enough clearance to pull the ESP module rearwards and rotate it 90 degrees so that the pump power post was moved between the brake line and edge of the fender.

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LEONARD_85 · 2026-09-04T16:01:49-0400

LAZARU5 said:
Based upon my diagnostics efforts (coached by ChatGPT) I am fairly confident that the ESP module in my 2004 SLK320 needs to be replaced…..

[/eQUOTE]

Hello can you elaborate how you came to this task? It seems like you’re applying great effort with no guarantee of a resolved issue - what was your issue?

LAZARU5 · 2026-09-04T16:01:49-0400

After reconnecting the ESP module and negative battery post I ran a full scan with a Launch x431 before starting the engine. The only remaining code was an Instrument Cluster error, B1041, indicating failed communication with traction control module. After starting the engine I was able to clear this code. The CEL, brake wear, BRAKE, ABS, and BAS/ESP lights are now off. The speedometer and odometer are also working.

The 170-545-01-32 Q06 ESP module from a donor 2002 SLK230 works in my 2004 SLK320 without any special configuration. Not sure if a module with a Q04 or Q05 revision level would have worked to replace the original Q06 version.

LEONARD_85 · 2026-09-04T16:05:14-0400

Sorry is that your reply to my earlier post using AI?

LAZARU5 · 2026-09-04T17:32:32-0400

@LEONARD_85, here is my reply to your question which I did not see when you posted it.

Original issues were CEL, brake wear, BRAKE, ABS, and BAS/ESP lights on and speedometer and odometer not working after spending a week parked outdoors with a lot of rain. Five different codes were reported by the Launch x431: P1999, P0600, B1041, P0341, and B1453. I described the symptoms to ChatGPT and it concluded that there were multiple unrelated issues.

I attempted to resolve the P0341 CPS issue by installing a second new CPS. After that failed I made a terminal probe to check the CPS connector wires. Before doing any continuity or voltage tests I discovered that the 0.110" by 0.030" test probe I made had virtually zero friction in the #3 12v pin of the CPS connector. I managed to snug up the fit in the #3 terminal to feel like the fit in the #1 and #2 terminals and was able to clear the P0341 error.

The B1453 error cleared up after removing and replacing the #37 5A fuse. The fuse was not blown but the blades were cruddy looking.

When I got down to the ESP related codes I did not start by ordering a replacement ESP module. I uploaded the two pages of wiring diagram schematics showing the ESP connector to ChatGPT as well as photos of the backside of the ESP cable connector before mapping out the test procedures. After exceeding the upload limit and having to wait a few hours to upload more I decided to purchase a one month ChatGPT subscription for $20 to speed up the process.

ChatGPT coached me through testing the F3 50A fuse in the prefuse fuse box, the #45 and #47 12v pins in the ESP connector, the #44 and #46 ground wires in the ESP connector, and the CAN bus #15 and #16 pins. I made test probes that matched the dimensions of the power pins #44 thru #47 and the smaller pins in positions #1 through #43. ChatGPT explained how to test the 12v and ground pins under load. After doing all the cable testing and not finding any unexpected results ChatGPT concluded that the ESP module was the likely issue.

LEONARD_85 · 2026-09-07T06:47:06-0400

Thanks so prior to being parked in the rain there were no issues? Or were there symptoms when driving the car…

slk230red · 2026-09-05T09:04:11-0400

LAZARU5, Nice write up...might help others having the same issues. Just to add, I had to replace the module on my '01 SLK230 due to the ABS Pump running continuously even with engine off/key out. My old one was a Q5 and replaced it with a donor Q6.

LAZARU5 · 2026-09-05T09:18:36-0400

I was wondering if it was okay to mix the pump and ESP module with non-matching Q0x versions. I specifically looked for a Q06 ESP module to match the original one in my car. You used a higher rev level, I wonder if a Q05 ESP module would work with a Q06 pump.

slk230red · 2026-09-05T20:09:34-0400

My guess is that it would work. In my case, I found a wrecked SLK230 the same year as mine. I went to look at it before I made the purchase, the car was not hit in the front so they sold me the pump/module assembly for $150.
Original Module:

Replacement module:

LAZARU5 · 2026-09-07T22:32:23-0400

@LEONARD_85, I don't think being parked in the rain caused any of the underlying issues, but the humidity and temperature changes may have helped flush out some the lurking electrical gremlins. It seemed very odd that everything was okay and then suddenly I was dealing with three unrelated failures - CPS connector, HVAC fuse, and ESP module communication errors.

I do have one final update about an extremely embarrassing diagnostic failure. ChatGPT was guiding me through a logical progression of diagnostic tests, but I made an expensive assumption and unnecessarily replaced the ESP module. After resolving the CPS and recirculating air flap issues I focused on the more critical ESP errors.

In addition to the tests I outlined in post #16 above, I thought I had ruled out an issue with the switched 12v power to the ESP module when I confirmed that all five ATC fuses on the K40 had 12v on both sides of each fuse with the ignition on. After replacing the ESP module I was able to clear all the stored error codes and took a short drive to verify the speedometer and odometer were working.

The following day when I started the car the three ESP module related errors returned. This time I made the extra effort and made a jumper probe to test for ignition switched 12v on pin #18 of the ESP module connector. It read 0v. I took the K40 module out and a bench test revealed that the traction control relay was not working with B5 grounded and +12v connected to D2. I replaced the K40 module with a used spare unit I had recently purchased on eBay and the ESP module errors immediately cleared up. I do not have an explanation as to how I was able to clear all the error codes after swapping out a working ESP module.

Unfortunately, the spare K40 has an issue with the Air Pump relay, so I still have more work to do. Today, I removed the 2002 SLK230 donor ESP module and reinstalled the original SLK320 module. I updated ChatGPT after confirming the K40 relay turned out to be the real issue. ChatGPT apologized for not insisting that I check for 12v on pin #18 with ignition turned on.

Modified E6 torx socket for removing ESP module on FL R170

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