Yamaha MTN850-A 2017, Service Manual, Page: 451 / 560

FUEL INJECTION SYSTEM
8-94
Fault code No. P2122, P2123, P2127, P2128, P2138
TIP
If a fault code other than No. P2138 (P2122/P2123/P2127/P2128) is detected, perform troubleshooting
first.
7 Delete the fault code and check
that the engine trouble warning
light goes off.
Confirm that the fault code has
a condition of “Recovered”
using the Yamaha diagnostic
tool, and then delete the fault
code.
Fault code No. P2122, P2123, P2127, P2128, P2138
Item
[P2122] Accelerator position sensor: open or ground short circuit
detected.
[P2123] Accelerator position sensor: power short circuit detected.
[P2127] Accelerator position sensor: ground short circuit detected.
[P2128] Accelerator position sensor: open or power short circuit
detected.
[P2138] Accelerator position sensor: output voltage deviation error.
Fail-safe system
Able/Unable to start engine
Able/Unable to drive vehicle
Diagnostic code No. 14, 15
14
Tool display
Accelerator position sensor signal 1
•
12–22 (fully closed position)
• 97–107 (fully open position)
Procedure
• Check with throttle grip in fully closed position.
• Check with throttle grip in fully open position.
15
Tool display
Accelerator position sensor signal 2
•
10–24 (fully closed position)
• 95–109 (fully open position)
Procedure
• Check with throttle grip in fully closed position.
• Check with throttle grip in fully open position.
Item
Probable cause of malfunc-
tion and check
Maintenance job
Confirmation of service com-
pletion
1 Connection of accelerator posi-
tion sensor coupler.
Check the locking condition of
the coupler.
Disconnect the coupler and
check the pins (bent or broken
terminals and locking condition
of the pins).
Improperly connected

Con-
nect the coupler securely or
replace the wire harness.
Turn the main switch to “ON”,
and then check the condition of
the fault code using the mal-
function mode of the Yamaha
diagnostic tool.
Condition is “Recovered”

Go
to item 8 and finish the service.
Condition is “Detected”

Go to
item 2.
Fault code No. P1606, P1607
Item
[P1606] Intake air pressure sensor 2: ground short circuit detected.
[P1607] Intake air pressure sensor 2: open or power short circuit
detected.