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SERVICE URGENT - Error code P0155 - invalid signal

WroomWroom

WroomWroom

Tuned and Synch'ed
GT Contributor
Joined
Jan 25, 2015
Messages
59
Location
San Jose, CA
Hi all,

I got the "SERVICE - URGENT" message while riding some time ago, and when it showed up the throttle seemed to be limited - engine wouldn't rev over 4K RPM, and there seemed to be a cut-off in throttle signal past a certain degree of throttle handle.

I pulled over, turned the bike off, turned it back on and the service message disappeared.

Once I got home I plugged the laptop in and used GuzziDiag to pull the error code out. Code was "P0155 Invalid Signal". I searched the web for some further details and kind of hit a wall, I couldn't find anything specific to Guzzis. I then searched for Aprilia and it seems like on Tuonos that error code means signals coming in/out of throttle position sensor are invalid. At first I thought I'd have to replace the whole sensor ($350+) but once I got the fuel tank off I realized that the sensor has two metal pipes that serve as "leads" for the two throttle cables and that one of the pipes had its tightening screw loose so the pipe was moving left/right.

Tightened both pipes down and the problem hasn't showed back up yet.
 
Nice detective work. It's always great to find a cheap fix. Also it sounds like an issue which may occur on other bikes. It's always good to have the info out there where it can be found.
 
P0155 = Throttle Grip Position Redundancy tracks C-D inconsistent signal. I believe there are four potentiometers (A,B,C & D), all have to produce valid signals. Only the Cali 1400 has this, and when the error was found, the motor was placed into a "Limp Home" mode.

Let's hope your fix worked, it could get expensive otherwise.
 
kiwi dave said:
P0155 = Throttle Grip Position Redundancy tracks C-D inconsistent signal. I believe there are four potentiometers (A,B,C & D), all have to produce valid signals. Only the Cali 1400 has this, and when the error was found, the motor was placed into a "Limp Home" mode.

Let's hope your fix worked, it could get expensive otherwise.
Click to expand...

I'm 99% sure the fix worked - I managed to induce the symptom by messing and pulling at the two throttle cables before turning the bike on, but other than that it hasn't showed up since.

The potentiometers are definitely very sensitive, I think people who made changes to their handlebars are potential "customers" for this problem... I installed Todd's handlebar raisers plus I rotated the handlebar some more towards me, I think that's when the throttle cable lead on TGPS got loose.
 
Had the same issue on the final day of a week long tour. "SERVICE-URGENT" flashing, had to ride 100m to a service station for fuel, bike was obviously in 'limp home' mode, sluggish, stalled twice. Refuelled, and on startup, "SERVICE URGENT" wasn't flashing, but steady. Rode 180km with normal power to next fuel stop. On restart, no service message. Refuelled in my home town, still all good. Rolled into my garage and "SERVICE URGENT" appeared again and bike was in 'limp home' mode. Shut down and restarted bike, no message. Connected Guzzidiag which showed 'PO155' code as 'read' but not stored. Cleared code. Shifted fuel tank to inspect the throttle cables entering the sensor - all normal. Steel guide tubes tight and straight. Bar risers fitted, but cable routing is normal and free. Bike has 37,000km. Bike is not showing any service codes now and starts normally.

Stephen
 
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