My BMW S1000XR Motorcycle Left Me Stranded!

What really happens when your motorcycle goes into limp-home mode.

Beemer left me stranded
With a little help from strangers, the XR gets loaded onto the flatbed truck. Something seriously wrong in the ride-by-wire system threw it into the limp-home mode.©Motorcyclist

No warning. Nothing. I was riding my long-term BMW S1000XR home from the dealership that had just committed the 18,000-mile service when, without a stumble or hesitation, power cut out. I was in the middle of a transition road from one freeway to the next with enough velocity in my pocket to clutch it and glide over to the shoulder.

Because there wasn’t much traffic, I was able to get there safely and have time to flip the engine kill switch to off, then to run, and then to try an engine restart. It did, and I seemed to have full power. So while still rolling, I pulled back into traffic and began wondering just what kind of glitch that could have been, hoping it wouldn’t recur in the remaining six miles back to my house.

No such luck. Half a mile later, the engine cut out again. Once more, I drifted to the shoulder and tried the kill switch. This time, though, while the engine would restart, there was no response from the throttle grip. Just a high idle of around 2,500 rpm, and a tiny bit more if I twisted the grip wide open. I noted the check-engine light was on and figured the BMW had suffered some sort of ride-by-wire failure. Something fairly big.

I was able to eke out 25 mph in second gear in the limp mode, so I turned on the hazard lights and rode the shoulder to the next off ramp. It was mid-afternoon in Long Beach, so traffic was still fairly light. I was more peeved at possibly missing an appointment that afternoon than i was concerned for my safety retreating from the highway.

Off the highway, I found a safe spot to park and consider my options. There was nothing obviously amiss with the BMW's throttle spool, and the bike was making no funny sounds or smells. The failure was virtually instant and repeatable; every time I tried restarting, the bike ran for a couple of seconds properly then lighted the check-engine icon and went to the high-idle mode. Even pulling the negative battery cable, waiting a minute, and reinstalling didn't fix the problem, which told me it wasn't some stray electronic or computer glitch but something more mechanical.

Cook waits for the tow truck.
Happy to find some shade on a warm late-spring day, Cook waits for the tow truck.©Motorcyclist

Maybe, just maybe the limp-home mode would provide enough power to get me home via the quieter city streets. There was just one problem, a freeway overpass between me and the relatively flat lands of downtown Long Beach. I attempted one crossing of the bridge and soon realized the engine wasn’t making enough power to climb it, even in first. I was down to a walking pace with no sidewalk or runoff area to protect me.

That’s it. I’m not going anywhere. Time to call for help.

BMW offers roadside assistance for all its new bikes, but I first tried calling the local dealer, BMW Motorcycles of Long Beach, only to be told they don't have a way to come fetch broken bikes. I got through quickly to the roadside assistance operator who asked for the last few digits of the ibk'e VIN, my location, and the nature of my problem. She then put me on the line with a technical consultant. After I quickly described everything I'd tried—no, the bike is not out of gas, the sidestand is up, I have tried cycling the key—he agreed there was nothing more I could do. A flatbed truck would be there in about an hour. It was there in less time than that and got the XR to the dealership without complication or charge. But it was also Friday afternoon, so I'd have to wait out the weekend to learn what had failed.

I got a call from service on Monday and filled in some of the back story; that the bike had just had its 18K service completed by another dealer. “Well whoever did that managed to put the throttle bodies back on and trap the wiring harness. Eventually one of the wires was worn through, and that’s why the engine stopped.”

Makes total sense. In any RBW system, the bike’s main computer looks at several sensors to determine when and how far to open the throttle plates, which are not physically controlled by the rider. The ECU compares what you’re requesting at the throttle grip to a pair of sensors on the throttle rack itself, one that’s part of the drive motor that, in effect, says, “Here’s where the throttle plates should be.” And there’s another, separate sensor that confirms, “Yes, that’s how far they’re open.” If any of those key sensors disagree, the ECU goes into a safe mode. You certainly don’t want a bike as powerful as the XR to default to maximum power, do you? The broken wire took one of those sensors out of the loop.

This is only the second RBW failure I've experienced, and I ride a lot of bikes with the technology. The other one was a sensor that went out of spec, but it cleared itself and I was able to ride the bike back to the shop. In this case, the BMW's problem had nothing to do with the XR being an electronically sophisticated motorcycle. It had everything to do with a maintenance mistake.

Arriving at Long Beach BMW
Arriving at Long Beach BMW on a Friday afternoon, the XR’s maladies remained a mystery through the weekend.©Motorcyclist