2.5 Hybrid: P0811 code OBD2

[DreamWeaver21]

Well, no update from the Dealer. No call from them either. I did call and leave a message.... Ford app shows 12 vehicle alerts now. Hoping @Ford Motor Company is watching this thread and can help escalate...

With FORScan you can program the modules in hex but I am not sure if it will display the data values in hex. It is free to download and you can get a trial license. The recommended connector is pretty cheap as well. I would just get it and see.

I don't have access to mine at the moment to check it.

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[Thex]

With FORScan you can program the modules in hex but I am not sure if it will display the data values in hex. It is free to download and you can get a trial license. The recommended connector is pretty cheap as well. I would just get it and see.

I don't have access to mine at the moment to check it.

HAHA - Not sure if they would want me in their shop with my own computer. And I dont know what their definition of bricked is.... it may not be readable...

 

[casanewt]

New incident for me on a recent road trip. I had the check engine light activate once on me back in May when I was on the interstate with cruise set around 75 MPH and I hit the accelerator to go around someone. Just the Yellow/Orange light and it disappeared a day later. On this last trip, same scenario, but the vehicle threw a RED powertrain failure light and went into limp mode. The dash instructed me to pull over when safely possible. Power to accessories(but not HVAC) was on, but drivetrain was not functioning. Luckily, once I got over to the shoulder, I was able to reset the vehicle by doing a complete shutdown of the vehicle. It took a couple of tries, but it came back to life. We were able to continue on with no issues at all other than a Yellow/Orange engine light that disappeared in a couple of hours of continued interstate driving. It was a crazy scenario though and a step up from the first incident. @Ford Motor Company

Reposting this to keep the issue front and center. This has happened to me three different times, all in very similar scenarios. Note that the only way to get a full reset was to turn off truck and slightly open the door to fully shut down before powering back on. It is very concerning that some dealers are doing transmission repairs. This really seems like more of a sensor/programming issue since my experience is that after the power cycle, the truck is fine. It is definitely a major issue since the truck can drop into limp mode while you are at highway speeds and require you to navigate to the shoulder while in traffic. @Ford Motor Company

 

[skinnyboy]

Very disconcerting safety issue that you are experiencing, hopefully it can be resolved!

I think you hit the nail on the head in suspecting a sensor/programming issue.

My Maverick has thrown up a number of doobie little fault messages on the info screen. All went away on their own, so does make me suspect the parameters for sensor inputs are too narrow in the software, poor quality sensors that drop out of range on occasion, or poor wiring. Probably a combination of these.

And of course the inconsistent braking transition at low speed.

Great vehicle with poor programming.

Good luck!

 

[Neils Bohr]

I have some interesting data to report:

I did some more full-throttle acceleration tests since the last one I described in my previous post. Unlike before I found that the driveline happily increased power to 100% and the Power Gauge needle stayed there (!), without any (noticeable) clutch slippage.

After several tests over several days, I am finding that the driveline performs as it should.

The question is now: why is it suddenly working?

I am cautiously concluding that the damper/clutch located between the internal combustion engine and the HF45 transaxle was likely slipping below its design torque rating.

And I can come up with various possible causes: maybe some slight inconsistencies in the friction material lining on the factory new clutch plate, maybe due to the fresh surface finish on the flywheel or pressure group, or maybe there is simply some remaining grease or oil (corrosion protection?) in the wrong location i.e on the friction surfaces.

Based on my observations it seems that if the Engine Control Module reads a discrepancy between expected ICE and transaxle RPM, it will restrict maximum driveline power. If the difference is significant it may set the OBD2 P0811 code (which it did twice on mine), but on small discrepancies, it may just restrict engine power i.e. my truck not wanting to exceed 70%.

I think that putting some good engine load on this clutch/damper in my truck caused it to slip several times and may have "bedded" the friction surfaces sufficiently that there is no more unwanted slip happening.

Note that this is all theory on my part, but it seems like a reasonable explanation. And If I have it wrong I stand ready to be corrected of course.

I will be monitoring this situation on my truck, but so far it looks like the issue may have resolved itself.

I also reported this issue to Ford, and also how it appears to have been resolved.

I am hoping this information helps some other Maverick Hybrid owners here and I will report back if anything changes on this end.

Has it been okay since you posted this? I am getting same error codes under same conditions as you in my 2023 hybrid.

 

[MakinDoForNow]

What was your diagnosis? I have not seen this issue (yet) and I've really gunned it a few times merging onto a freeway (in sport mode even).

Sport mode, I believe keeps ice running and that might lower the possibility of computer interactions being affected in rapid response if ice happens to be off.

 

[Glen Baker LLC]

Has it been okay since you posted this? I am getting same error codes under same conditions as you in my 2023 hybrid.

"Neils Bohr"
Take a look at page 4 post #54
Hopefully that answers your question.

 

[mav47]

@Neils Bohr

The codes went away, kind of what I was expecting. If I recall correctly I must have had maybe five or six of these P0811s, all early on, with decreasing frequency.

So my theory seems correct: the slippage events resulted in bedding-in of the friction clutch surfaces (aka the transmission damper), and with that the clutch friction increased sufficiently and the problem simply resolved itself.

Once the friction in this break away clutch is higher than the torque the engine can produce, it will never slip again, barring an impact load by a sudden blocking of the input or output shaft while it is spinning (which is why this safety clutch is there in the first place).

I currently have 62k miles on the truck, and I tow a camp trailer around max. tow rating regularly. Haven't had any issues, and don't expect any.

Disclosure: I work in a field where I deal with vehicle electrics and also with friction materials, so I am quite familiar with the technology involved.

The friction clutch in your "23 Hybrid may have had some slight greasy surfaces, or maybe a less than perfect flatness. This is the most likely scenario here.

My advice at this point: do a few full throttle acceleration runs, that may cause it to slip and allow it to throw the P0811 code. The code goes away after a day or so, after a few of these you likely won't see them again, unless there's the (unlikely) case of something else being wrong like maybe a leaky main crank seal or so.

Cheers!

 

[The Real Maverick]

If it starts to "rattle" after a few weeks / months you'll know the problem is not going away.

 

[mav47]

@The Real Maverick

In my opinion any rattle or noise from the clutch/damper between the engine and the HF45 transaxle would be caused by play/mechanical tolerance in the clutch/damper assembly. This would be a completely different issue which I assume cannot throw a P0811, or any other error code as it is difficult to detect electronically?

Do you know if that clutch/damper rattle you describe is a somewhat common issue in these drivelines? I haven't read about it, but that doesn't mean anything of course!

Either way, as far as I know P0811 is set by a mismatch between ICE RPM and transaxle RPM, which can only be caused by slippage, so would be friction related.

Given that @Neils Bohr had P0811 indications, it is most likely the same situation as mine.

Please report back after some time, @Neils Bohr !

Cheers!

 

[Neils Bohr]

@Neils Bohr

The codes went away, kind of what I was expecting. If I recall correctly I must have had maybe five or six of these P0811s, all early on, with decreasing frequency.

So my theory seems correct: the slippage events resulted in bedding-in of the friction clutch surfaces (aka the transmission damper), and with that the clutch friction increased sufficiently and the problem simply resolved itself.

Once the friction in this break away clutch is higher than the torque the engine can produce, it will never slip again, barring an impact load by a sudden blocking of the input or output shaft while it is spinning (which is why this safety clutch is there in the first place).

I currently have 62k miles on the truck, and I tow a camp trailer around max. tow rating regularly. Haven't had any issues, and don't expect any.

Disclosure: I work in a field where I deal with vehicle electrics and also with friction materials, so I am quite familiar with the technology involved.

The friction clutch in your "23 Hybrid may have had some slight greasy surfaces, or maybe a less than perfect flatness. This is the most likely scenario here.

My advice at this point: do a few full throttle acceleration runs, that may cause it to slip and allow it to throw the P0811 code. The code goes away after a day or so, after a few of these you likely won't see them again, unless there's the (unlikely) case of something else being wrong like maybe a leaky main crank seal or so.

Cheers!

Excellent info thank you!

 

[Neils Bohr]

@The Real Maverick

In my opinion any rattle or noise from the clutch/damper between the engine and the HF45 transaxle would be caused by play/mechanical tolerance in the clutch/damper assembly. This would be a completely different issue which I assume cannot throw a P0811, or any other error code as it is difficult to detect electronically?

Do you know if that clutch/damper rattle you describe is a somewhat common issue in these drivelines? I haven't read about it, but that doesn't mean anything of course!

Either way, as far as I know P0811 is set by a mismatch between ICE RPM and transaxle RPM, which can only be caused by slippage, so would be friction related.

Given that @Neils Bohr had P0811 indications, it is most likely the same situation as mine.

Please report back after some time, @Neils Bohr !

Cheers!

It sounds what is happening to me is the same as what happened to you. I have had the code a couple of times. I have tried accelerating fast and aggressively over the past few days and so far I haven;t been able to reproduce the code. I will continue to try the procedure that MAV 47 outlined here and there to see how that works out. Haven't heard back from the dealership so far. Not in a rush to replace the damper if I can have this friction "bed in " procedure work for me too!

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