"Fault in the engine control" warning on R18B

[BeemeR18]

Quick update on this issue, unfortunately still no luck.

The bike went to BMW Motorrad for around 2 hours of diagnostics/troubleshooting using ISTA. The main fault they've investigated was 3A1112 (Component Group 1 over-current) but surprisingly, their ISTA did not provide any more detail as to what the fault was (i.e. did not say 'fuel pressure sensor' or 'crank position sensor' whatever).
They followed the ISTA test plan, disconnecting the Group 1 components, but couldn't isolate the cause. I got the bike back with the same fault and no conclusive diagnosis.

Since I've already ordered the fuel pump, I did the following:

• Replaced the entire fuel pump assembly with a brand new unit (no change).
• Disconnected the fuel vent valve (no change).
• Disconnected all four O2 sensors (no change).
• Removed the fuel tank and disconnected the throttle body and fuel pump while inspecting the under-tank wiring loom. I couldn't find any obvious chafing or damage...

Cancelled a motorcycle trip and still no idea what's causing this, any thoughts?

 

[bdalameda]

This is all I have found:
BMW error code 3A1112 (often displayed as "DME: Fuse active: Component group 1") indicates an overcurrent or short circuit has tripped an electronic safety fuse inside the engine computer. This usually disables power to a specific circuit, often affecting fuel injectors or the exhaust servo. [1, 2, 3]

Most Common Causes

• Exhaust Flap Servo: This is the most frequent culprit. The servo motor can bind, jam, or short out due to debris or wear, instantly tripping the fuse. [1, 2]
• Wiring Harness Damage: Pinched, frayed, or grounded wires (often near the steering head or exhaust) can cause the system to short. [1, 2, 3, 4]
• Failed Fuel Injectors: An injector failing electrically or drawing excessive current will trigger this fault.[1, 2]
• Low Battery Voltage: BMW engine management computers are highly sensitive to voltage drops. A weak battery or corroded terminals can cause erratic faults. [1, 2]

Recommended Action Plan

1. Check the Exhaust Servo: Disconnect the exhaust flapper servomotor and try clearing the code. If the code does not return, the servo is likely internally shorted or jammed and needs replacement or a bypass. [1]
2. Inspect the Wiring: Carefully check the wiring looms connecting to your fuel injectors and exhaust valve for any exposed wires or melting. [1, 2]
3. Test Your Battery: Ensure your battery is putting out adequate voltage and pass a load test. [1]
4. Read Live Data: Use an OBD2 adapter with an app like MotoScan or a dedicated BMW diagnostic tool like the GS-911 to pinpoint exactly which sensors or actuators are drawing excess current. [, 2]

 

[bdalameda]

Also disconnect all the ignition coils. Clear the codes and then plug each coil in and see if one sets the error code. This will determine which ignition coil may be setting the code. The same thing can be done with the fuel injectors.

 

[Ulrich]

... hmmm

Also disconnect all the ignition coils. Clear the codes and then plug each coil in and see if one sets the error code. This will determine which ignition coil may be setting the code. The same thing can be done with the fuel injectors.

... wouldn't a disconnected coil also throw an error? just not an 'overcurrent' error ... is that what you are going for? ... just curious ...

 

[bdalameda]

... hmmm

... wouldn't a disconnected coil also throw an error? just not an 'overcurrent' error ... is that what you are going for? ... just curious ...

Yes you will but you will not see a DME error only the coil error. This is how you diagnose the same error on a K1600 6 cylinder. Disconnect all coils and plug each one in at a time until the DME Fuse error occurs.

 

[Star-Lord]

I'm bothered that this issue is still outstanding... Stupid question... Have you walked around the bike, and checked all of the lights.. directionals.. brake light, etc.. make sure it isn't something silly..

 

[BeemeR18]

I can't seem to figure it out, here's what I've done so far:

Disconnected and cleaned contacts of:
4 Ignition Coils + swapped 2 new coils to test
4 Oxygen Sensors
2 Exhaust Servo Eliminators (actual servo is gone)
Crank Position Sensor
Cam Position Sensor
Fuel Pressure Sensor
Fuel Vent Valve
Fuel Pump/Fuel Level assembly + replaced pump
Throttle Body
ECU (?!)
Level Sensor/Suspension Adjustment/Final Drive sensor even though not directly relevant

+ Cleaned Fuses and Battery terminals

Nothing seems to clear this error, lots of restarts and clearing codes with each component disconnected to see if anything changes, code is still there.
At some point I had most of the list above just left disconnected, tried to clear codes, but 3A1112 fault keeps coming back..

For the past 3 days I've been inspecting the harness around the frame and around the connectors, looking for any visible wear/chafing but everything seems okay, plus it's a 2022 bike not much wear is expected on the harness (no rodents or other damage either so I'm puzzled).

Since the tank was off I started stripping off the tape from the harness on the side with the fuel pump wiring, just to inspect the wires inside:

No visible damage to the insulation, everything is spot on as expected for a bike this age...

 

[Ulrich]

This is the most bizarre thing ever ... I am so sorry that this is ruining your riding fun!

 

[Mac]

I maybe way off but I remember the coding was altered on my older r1250rt a couple of years ago by BMW to not check the exhaust valves every time. For the life of me I cannot remember for definitely how often the bike checked the range of motion but it was done to make sure the exhaust valves had definitely gone out of spec as opposed to just occasionally. The code was changed to stop so many bikes ending up with the light on the dash in their words ‘unnecessarily’ and subsequent warranty claims. As my bike was on its second set of headers at two years old I could see the rationale. I know you swapped around the servo eliminators but my thinking is that if the coding is the same on the R18 it may not allow the error to be cleared until it has completed its programmed error check sweep which is done I understand when you first turn the ignition on but not every time. The only fault that comes up on the eliminators when I did a search for the fault code you have is a potential short circuit. Do you by any chance still have the original servos to temporarily plug in and try multiple attempts to turn on and off. From a vague memory my RT used to check the vales roughly once in every ten ignition cycles. As I said I could be way off but just throwing out ideas as you seem to have covered everything other than an ecu blip/fault which a software update may well fix. Good luck.

 

[BeemeR18]

Quick update on the 3A1112 saga, and an unexpected twist.

First, thanks everyone for the help. I realised my first post was over a month ago… definitely one of the most challenging troubleshooting exercises I’ve ever had on a motorbike.

Since my last post: On Saturday I spent another ~3 hours going over connectors and the harness again. Still no change. I started re‑bandaging the exposed sections and basically gave up for the day. Before heading out (Iron Maiden at Knebworth Park, amazing), I randomly reconnected the trickle charger, haven't used it since the error first came up.

Sunday I didn’t touch the bike. Instead, I drafted an email to the dealer I bought it from last year. I did flag the error to them back then, and they had opened a case, but after the BMW recall + software update in November, the fault never resurfaced until now.

Monday morning: I called them, explained the persistent fault and the inconclusive BMW diagnostic. By 4pm they replied saying they’d reviewed the case and would send a van to collect the bike for inspection/repair. I honestly couldn’t believe it. They only asked for fresh photos of the bike’s condition.

So I went to the garage to put everything back together for the photos. I jacked the bike up, switched on the ignition to take a picture of the error and mileage… and the error was gone. Even the warning light on the right side of the dash was gone for the first time since June. Fuel gauge was reading weird (150%), but still.. no error.



Plugged in the OBD:

• 3A1112 was not active anymore.
• Two new O2‑related codes appeared.
  • I swapped in my spare O2 sensors → cleared codes → restarted → all four O2s showed errors.
  • Cleaned connectors again → reconnected the bike ones → cleared codes → restarted → only the right O2 fault remained.
  • Cleaned that connector once more → cleared code → restarted → ran the engine for ~2 minutes → OBD finally showed No Active DTCs for the first time since June.
    

Now the big question: I’m trying to work out what could have caused a fault this persistent. The only theory I can come up with is something like:

• Slightly loose battery connector + corroded fuse terminals → inconsistent voltage
• Voltage drops = current spikes → ECU sees over‑current in Component Group 1
• A dodgy front‑right O2 connector may have been hidden behind the broader 3A1112 'Group 1' fault
• Repeated ignition cycles without running the engine degraded the battery further
• I avoided the trickle charger thinking it caused issues, so the battery may have dropped low enough to keep the ECU stuck on the over‑current fault
• Once the battery terminals and fuses were properly cleaned and the charger reconnected, the ECU finally had stable voltage and the underlying O2 issue surfaced - and once that was fixed, everything cleared?

Is that even remotely plausible? Or am I looking at a bike with a deeper underlying problem that just hasn’t shown itself yet?

Should still let the dealer take it, or keep the bike now that the fault has cleared? That’s really what I’m trying to figure out.

 

[Mac]

Quick update on the 3A1112 saga, and an unexpected twist.

First, thanks everyone for the help. I realised my first post was over a month ago… definitely one of the most challenging troubleshooting exercises I’ve ever had on a motorbike.

Since my last post: On Saturday I spent another ~3 hours going over connectors and the harness again. Still no change. I started re‑bandaging the exposed sections and basically gave up for the day. Before heading out (Iron Maiden at Knebworth Park, amazing), I randomly reconnected the trickle charger, haven't used it since the error first came up.

Sunday I didn’t touch the bike. Instead, I drafted an email to the dealer I bought it from last year. I did flag the error to them back then, and they had opened a case, but after the BMW recall + software update in November, the fault never resurfaced until now.

Monday morning: I called them, explained the persistent fault and the inconclusive BMW diagnostic. By 4pm they replied saying they’d reviewed the case and would send a van to collect the bike for inspection/repair. I honestly couldn’t believe it. They only asked for fresh photos of the bike’s condition.

So I went to the garage to put everything back together for the photos. I jacked the bike up, switched on the ignition to take a picture of the error and mileage… and the error was gone. Even the warning light on the right side of the dash was gone for the first time since June. Fuel gauge was reading weird (150%), but still.. no error.

View attachment 21878

Plugged in the OBD:

View attachment 21879

• 3A1112 was not active anymore.
• Two new O2‑related codes appeared.
  • I swapped in my spare O2 sensors → cleared codes → restarted → all four O2s showed errors.
  • Cleaned connectors again → reconnected the bike ones → cleared codes → restarted → only the right O2 fault remained.
  • Cleaned that connector once more → cleared code → restarted → ran the engine for ~2 minutes → OBD finally showed No Active DTCs for the first time since June.

Now the big question: I’m trying to work out what could have caused a fault this persistent. The only theory I can come up with is something like:

• Slightly loose battery connector + corroded fuse terminals → inconsistent voltage
• Voltage drops = current spikes → ECU sees over‑current in Component Group 1
• A dodgy front‑right O2 connector may have been hidden behind the broader 3A1112 'Group 1' fault
• Repeated ignition cycles without running the engine degraded the battery further
• I avoided the trickle charger thinking it caused issues, so the battery may have dropped low enough to keep the ECU stuck on the over‑current fault
• Once the battery terminals and fuses were properly cleaned and the charger reconnected, the ECU finally had stable voltage and the underlying O2 issue surfaced - and once that was fixed, everything cleared?

Is that even remotely plausible? Or am I looking at a bike with a deeper underlying problem that just hasn’t shown itself yet?

Should still let the dealer take it, or keep the bike now that the fault has cleared? That’s really what I’m trying to figure out.

Wow, some signs of getting there. Personally I would still let the dealer pick up the bike. Their equipment may expose historical codes that could clear this up and stop you looking for that fault light constantly. I am guessing you need some confidence in the bike by now, I would for sure. I would be looking for a definitive clear. By the way which dealer?

 

[Star-Lord]

I would try and ride the bike as much as possible, between now and the time that the dealership picks up the bike; even better, ride it to the dealership... At least have the dealership unfaaaak your fuel gauge..

Is the new fuel pump currently installed, possibly causing the fuel gauge error?

 

[BeemeR18]

I was planning to go on a ride and see how it runs or if it throws any more errors under usage.

I'm a bit hesitant handing it back because it's not an official BMW dealer, so I kind of doubt their ability to properly troubleshoot newer BMWs because of their complexities.

Seeing that I can't get to the bottom of it, I reached out to the dealer hoping to A. get them to repair it since the error was known or B. get the money back and find another R18B.

@Mac this is SBF which you would've heard of in the UK, so far they've been quite responsive so can't complain about the customer service.

@Star-Lord no idea what happened with the fuel gauge but slowly coming back to the correct range..

 

[Mac]

I was planning to go on a ride and see how it runs or if it throws any more errors under usage.

I'm a bit hesitant handing it back because it's not an official BMW dealer, so I kind of doubt their ability to properly troubleshoot newer BMWs because of their complexities.

Seeing that I can't get to the bottom of it, I reached out to the dealer hoping to A. get them to repair it since the error was known or B. get the money back and find another R18B.

@Mac this is SBF which you would've heard of in the UK, so far they've been quite responsive so can't complain about the customer service.

@Star-Lord no idea what happened with the fuel gauge but slowly coming back to the correct range..

In which case I wouldn’t let them have it back. They are a warehouse whose job is to sell without dealer overheads and almost certainly do not have access to BMW’s kit. Personally I have yet to find a good dealer in my neck of the woods. The service I had last week I was left with both brake reservoirs overfilled and leaking, just shoddy work. By all accounts a specialist like Boxer Works would be worth a try if after a few good rides codes start coming back. The trouble with off loading the bike is you are going to take a big hit at present if they do not give you your money back. Consumer Rights on second hand vehicles is a long winded process and they have the right to attempt to repair etc. As an aside I use RAC legal for advice and after a number of things like the misses car cloned etc it’s the best £15 a year I spend. It may help you to know what to say if you try to get your money back.

 

[Ulrich]

I am just glad that you are making some sort of process ... I am with StarLord ... ride it as much as you can before they pick it up ... oh one more question ... what is your voltage (measured with a meter not the bike display) with the ignition 'ON' ... maybe (it couldn't be that simple) you have a bad battery?

 

[BeemeR18]

Well I intended to ride the bike but.. fault came back.

Switched on, no errors, OBD showed No active DTCs still so I proceeded putting the last bits back so I can ride it, specifically:

Top engine covers
Side panels covering the Battery (L) and Relays (R)
Rectifier cover underneath, tidied up the wiring, zip-tied the rear O2 sensors wiring etc

Got all my gear on, bike running good, jumped on the bike, pulled clutch and reached for the side stand when the error popped up on the screen, I could not believe it.

One final thing, I joked about the fuel gauge but despite getting back to the usual range (i.e. it starts at E and goes up to 1/4 when switching on), I realised it's not showing the correct level?! I had a 10L petrol can, poured it into the tank but no change to the gauge, still showing 1/4 and even more so, Fuel Reserve warning came on.


I guess I have no other choice now but to have it collected/inspected.


PS. @Ulrich Voltage on screen shows 12.4V and measured was 12.56V - but this was after 2 days on the trickle charger, and error still active - I'll measure voltage again tomorrow, no longer on the charger.

 

[bdalameda]

Well I intended to ride the bike but.. fault came back.

Switched on, no errors, OBD showed No active DTCs still so I proceeded putting the last bits back so I can ride it, specifically:

Top engine covers
Side panels covering the Battery (L) and Relays (R)
Rectifier cover underneath, tidied up the wiring, zip-tied the rear O2 sensors wiring etc

Got all my gear on, bike running good, jumped on the bike, pulled clutch and reached for the side stand when the error popped up on the screen, I could not believe it.

One final thing, I joked about the fuel gauge but despite getting back to the usual range (i.e. it starts at E and goes up to 1/4 when switching on), I realised it's not showing the correct level?! I had a 10L petrol can, poured it into the tank but no change to the gauge, still showing 1/4 and even more so, Fuel Reserve warning came on.


I guess I have no other choice now but to have it collected/inspected.


PS. @Ulrich Voltage on screen shows 12.4V and measured was 12.56V - but this was after 2 days on the trickle charger, and error still active - I'll measure voltage again tomorrow, no longer on the charger.

Side stand switch fault??

 

[Ulrich]

Well I intended to ride the bike but.. fault came back.

Switched on, no errors, OBD showed No active DTCs still so I proceeded putting the last bits back so I can ride it, specifically:

Top engine covers
Side panels covering the Battery (L) and Relays (R)
Rectifier cover underneath, tidied up the wiring, zip-tied the rear O2 sensors wiring etc

Got all my gear on, bike running good, jumped on the bike, pulled clutch and reached for the side stand when the error popped up on the screen, I could not believe it.

One final thing, I joked about the fuel gauge but despite getting back to the usual range (i.e. it starts at E and goes up to 1/4 when switching on), I realised it's not showing the correct level?! I had a 10L petrol can, poured it into the tank but no change to the gauge, still showing 1/4 and even more so, Fuel Reserve warning came on.


I guess I have no other choice now but to have it collected/inspected.


PS. @Ulrich Voltage on screen shows 12.4V and measured was 12.56V - but this was after 2 days on the trickle charger, and error still active - I'll measure voltage again tomorrow, no longer on the charger.

Thanks ... that seems a bit low to me with just the ignition on ... but I could be wrong ... mine shows right under 13V (12.95) but it does drop if I leave the ignition on for a bit ... and you said the fault showed up with the engine running ... so power shouldn't be a problem ... I think this idea is a dead end also ... sorry ...

 

[Star-Lord]

Thanks ... that seems a bit low to me with just the ignition on ... but I could be wrong ... mine shows right under 13V (12.95) but it does drop if I leave the ignition on for a bit ... and you said the fault showed up with the engine running ... so power shouldn't be a problem ... I think this idea is a dead end also ... sorry ...

I've been checking my tire's TPS PSI sensor values for both tires, as well as the battery voltage while riding a LOT this week (I just topped off my air pressure) and the Model B battery reports 14.2 V consistently

Ohm's law will drive up current, at lower voltages; a bad battery putting out 10 V, will produce higher amperage to power a specific device(s). I remember reading the error codes were related to an over current condition; maybe it's something simple, like the battery..

What voltage reading does the bike report while running; perhaps, the stator isn't doing its job or a bad cell in the battery is loading down the electrical system..

I want this problem resolved, probably more than you...!!!!

 

[BeemeR18]

No wait, after disconnecting the trickle charger overnight I measured the voltage today, 12.36V measured with Ignition ON - but engine not running, if I start the engine I get 14.3-14.4V which should be correct.