FUEL INJECTION SYSTEM
8-58
Fault code No. 21
Symptom Open or short circuit of coolant temperature sensor lead
Fail-safe action
Engine startup: Possible
Riding: Possible
Diagnostic monitor-
ing code No.
D:06
Meter display
When engine is cold: Displays temperature closer to air temperature
When engine is hot: Displays current coolant temperature
Checking method
Compare the actually measured coolant temperature with the meter
display value.
Item/components and
probable cause
Check or maintenance job
Sensor inspection proce-
dure
1 Connection of coolant tem-
perature sensor coupler
Check the connection of the
coupler is secure.
Remove the coupler, and
check each pin (for bending,
wear, or locking).
Poor connection → Connect
it securely, or repair/replace
the wire harness.
Place the main switch to the
ON position, and check the
fault code indication.
No fault code indicated. →
Recovered.
Fault code indicated. →
Check the next step.
2 Connection of main harness
ECU coupler
Check the connection of the
coupler is secure.
Remove the coupler, and
check each pin (for bending,
wear, or locking).
Poor connection → Connect
it securely, or repair/replace
the wire harness.
Place the main switch to the
ON position, and check the
fault code indication.
No fault code indicated. →
Recovered.
Fault code indicated. →
Check the next step.
3 Connection of primary injec-
tor sub-wire harness coupler
Check the connection of the
coupler is secure.
Remove the coupler, and
check each pin (for bending,
wear, or locking).
Poor connection → Connect
it securely, or repair/replace
the wire harness.
Place the main switch to the
ON position, and check the
fault code indication.
No fault code indicated. →
Recovered.
Fault code indicated. →
Check the next step.
4 Continuity of wire harness Open or short circuit →
Replace the wire harness
Black/Blue–Black/Blue
Green/White–Green/White
Place the main switch to the
ON position, and check the
fault code indication.
No fault code indicated. →
Recovered.
Fault code indicated. →
Check the next step.
5 Installation status of coolant
temperature sensor
Check the mounting section
for a loose or pinched mount-
ing.
Make sure that the mounting
position is correct.
Place the main switch to the
ON position, and check the
fault code indication.
No fault code indicated. →
Recovered.
Fault code indicated. →
Check the next step.
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