TSB 25-2040 - Unintended Deceleration Without A Vehicle In Front When Using Adaptive Cruise Control Or BlueCruise

[Mach-Lee]

Well this is an interesting one. Some vehicles may experienced unintended or "phantom" braking using adaptive cruise control or BlueCruise when there are no cars in front of you. This may be due to unwanted radar sidelobe reflections hitting the front bumper which is positioned directly behind the front corner radar sensors. The front bumper can act as a waveguide and direct radar signals to the opposite side of the vehicle, and potentially allow the two front corner radars to interfere with each other, or pick up objects to the side and rear of the vehicle. The fix is to cover the open ends of the front bumper (red) with aluminum foil tape, which should prevent unwanted signal ingress. The front corner radar sensors are positioned below the headlights at a 45º angle relative to the vehicle axis and are used to detect vehicles in adjacent lanes for the assisted lane change and lane shift features of BlueCruise.

I will also mention that a damaged front adaptive cruise radar sensor (located centrally between the grille shutters) can also cause phantom braking if the sensor bracket is broken and the sensor is no longer aligned perfectly vertical. This can occur after a mild impact to the front bumper (such as being backed into, or hitting the chin on a curb). Issues with the front sensor may cause a false "car ahead" icon or braking associated with hills. I would recommend inspecting the front radar bracket during this repair as well to rule that out as a potential cause.

IMPORTANT NOTE: This TSB does not apply if a) you are getting collision warnings with the braking, or b) if you are seeing speed limit changes associated with braking. Those events are caused by separate issues.

TECHNICAL SERVICE BULLETIN Unintended Deceleration Without A Vehicle In Front When Using Adaptive Cruise Control Or BlueCruise	25-2040 12 February 2025​
Model: Ford 2021-2024 Mustang Mach-E Markets: Canada, USA Issue: Some of the vehicles listed in the Model statement above may exhibit an unintended deceleration without a vehicle in front when using ACC or BlueCruise. This may be due to the front bumper affecting both corner radar sensor signals. Action: For vehicles that meet all of the criteria in the Issue and Model statements, follow the Service Procedure to install aluminum foil tape to cover/close off the open ends of the front bumper. Parts Service Part Number Claim Quantity Package Order Quantity Description Obtain Locally​ As Needed​ As Needed​ Aluminum Foil Tape Obtain Locally​ As Needed​ As Needed​ Alcohol Wipes Claim Quantity refers to the total number of individual pieces required to repair the vehicle. Package Order Quantity refers to the amount of the service part number package(s) required to repair the vehicle. As Needed indicates the part is necessary but amount of the part may vary and/or is not a whole number. Parts can be billed out as non-whole numbers, including less than 1. Special Tool(s) General Equipment - Interior Trim Remover Warranty Status: Eligible under provisions of New Vehicle Limited Warranty (NVLW)/Service Part Warranty (SPW)/Service Part New Vehicle (SPNV)/Extended Service Plan (ESP) coverage. Limits/policies/prior approvals are not altered by a TSB. NVLW/SPW/SPNV/ESP coverage limits are determined by the identified causal part and verified using the OASIS part coverage tool. Labor Times Description Operation No. Time 2021-2024 Mustang Mach-E: Install Aluminum Foil Tape On Both Ends Of The Front Bumper Following The Service Procedure (Do Not Use With Any Other Labor Operations) 252040A​ 0.5 Hrs.​ Repair/Claim Coding Causal Part: 14C689 Condition Code: 04 Service Procedure 1. With the vehicle in N, position the vehicle on a hoist. Refer to WSM, Section 100-02 > Jacking and Lifting > Description and Operation. 2. Remove both stone deflectors and the lower air deflector to gain access to the front bumper from underneath. Refer to WSM, Section 501-19 > Removal and Installation > Front Bumper Cover. Perform only Step 3 and Step 8. 3. Using alcohol wipes, clean both open ends of the front bumper to remove any soil or debris to promote adhesion. 4. Using a minimum 2 in. wide (50 mm) by a minimum 6 in. long (150 mm) piece of aluminum foil tape, place the aluminum foil tape over each of the open ends of the front bumper as shown in Figure 1. Figure 1 5. Cut a long opening into the bottom of each of the aluminum foil tape on each front bumper end to allow a drain path for moisture as shown in Figure 2. Figure 2 6. Install both stone deflectors and the lower air deflector. Refer to WSM, Section 501-19 > Removal and Installation > Front Bumper Cover. Perform only Step 3 and Step 8. 7. Lower the vehicle from the hoist.

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[Spacey]

Do we take the vehicle in anyway? I'm loathed to take mine in as dismantling and refitting the bumper means more issues in case the refitting is not up to standard and paint is rubbed/scratched, gaps etc. An issue that should have been picked up on prototype testing. I've lost count the number of times I've taken in my vehicle for warranty items. Good job I'm retired with no need to take time off work. I'm less and less likely to get another Mach E at this rate. My first Ford could be my last.

 

[markboris]

Do we take the vehicle in anyway? I'm loathed to take mine in as dismantling and refitting the bumper means more issues in case the refitting is not up to standard and paint is rubbed/scratched, gaps etc. An issue that should have been picked up on prototype testing. I've lost count the number of times I've taken in my vehicle for warranty items. Good job I'm retired with no need to take time off work. I'm less and less likely to get another Mach E at this rate. My first Ford could be my last.

All that is required is to remove the stone deflectors on either side and the lower air deflector. There is no need to remove the entire bumper cover although I think it would be easier to fix this bumper issue if the cover was off. I've taken mine off a few times and it's not difficult at all.

Stone deflectors

Lower air deflector

 

[Paul H. Martinez]

This happens to me nearly every day. Didn't even realize its a known problem. Describes it exactly. Blue Cruise engaged at highway speed then inexplicable rapid deceleration. Sound like the same issue? Something the dealer would have the needed material for or would it require weeks to get?
Thanks

 

[Mike G]

Tinfoil elbow pads.

 

[N1naz]

Thanks for the info Mach-Lee,
This happened to me the other day without BC or ACC on. Going down my street with nothing in front of me the brakes came on and warning saying something like "xxxx in road". Scared the heck out of me. Came on and shut off within seconds.

 

[Fremont Kid]

Good to know. My MME was front-ended two weeks ago. Collision repair center is scheduled to release it today, after repairs and sensors calibration. I planned to drive on freeway to test out the blue cruise. Fortunately for me, I can return for more repairs - as described above, if this problem occurs.

 

[JohnFoxeSheets]

Interesting that, unless I missed it, the TSB doesn't give any info on eligibility beyond MY 2021-2024. Are dealers supposed to do this to all MMEs? Or just those where the owners complain about phantom braking? My car doesn't have phantom braking - but it does miss cars coming into my lane from just in front of me (i.e., the corner sensors don't appear to be detecting vehicles entering my lane from nearby). @Mach-Lee, I presume this TSB wouldn't help with that, right?

Also interesting that the TSB doesn't apply to MY2025s. I hope they make a part to cover the end of the bumper rather than have aluminum tape added in the factory!

 

[macchiaz-o]

the TSB doesn't give any info on eligibility beyond MY 2021-2024. Are dealers supposed to do this to all MMEs? Or just those where the owners complain about phantom braking?

It's a service bulletin, not a recall or satisfaction program. This only applies when a customer presents a concern that is correctable through this procedure, and it's at the customer's cost (or 3/36 warranty, if still eligible).

 

[JohnFoxeSheets]

It's a service bulletin, not a recall or satisfaction program. This only applies when a customer presents a concern that is correctable through this procedure, and it's at the customer's cost (or 3/36 warranty, if still eligible).

Thanks for the clarification, Jonathan. I have an 8-year extended warranty (which is see in the TSB is included), so I should be covered for an additional five years.

 

[moog]

I solved this issue long ago by wearing a tin foil hat while driving.

 

[Teslaeata]

Do we take the vehicle in anyway? I'm loathed to take mine in as dismantling and refitting the bumper means more issues in case the refitting is not up to standard and paint is rubbed/scratched, gaps etc. An issue that should have been picked up on prototype testing. I've lost count the number of times I've taken in my vehicle for warranty items. Good job I'm retired with no need to take time off work. I'm less and less likely to get another Mach E at this rate. My first Ford could be my last.

Don’t worry about the fitting of bumper, it’s only secured by fast-fit/release plastic clips and a few screws, I remove & refit bumpers at the roadside and all over the place all the time, it’s child’s play

 

[scott_77]

Not to be confused with the Predictive Speed Assist setting being on which happened to me numerous times when on highway going with traffic (10 over posted limit) and then suddenly braking only to finally realize it was every time posted speed limit came up... quickly turned that off...

 

[GreaseMonkey]

BC expires in 3 weeks and I will not renew, so good to go.

 

[kens]

I solved this issue long ago by wearing a tin foil hat while driving.

You take yours off? Why would you ever take it off?!

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