Operation Manual

FUEL INJECTION SYSTEM
8-47
Fault code No. 21
Item
Coolant temperature sensor: open or short circuit detected. (no nor-
mal signals are received from the coolant temperature sensor.)
Fail-safe system
Able to start engine
Able to drive vehicle
Diagnostic code No. d:06
Meter display Displays the coolant temperature.
Procedure
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.
Disconnect 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 wire harness
ECU coupler
Check the connection of the
coupler is secure.
Disconnect 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 Continuity of wire harness Open or short circuit →
Replace the wire harness
Black/blue–Black/blue
Green/red–Green/red
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 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.
5 Coolant temperature sensor
malfunction
Check in the diagnostic mode
(Code No. d:06).
During cold starting: A tem-
perature close to the ambient
temperature is indicated.
Indication is incorrect. →
Replace the coolant tempera-
ture sensor.
Sensor inspection procedure.
Refer to “CHECKING THE
COOLANT TEMPERATURE
SENSOR” on page 8-139.
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.