Elantra L4-1595cc 1.6L DOHC (1993)
Thermostat: Customer Interest
Engine - Won't Warm Up, DTC 21 Set
Group: ENGINE
Number: 92-20-009
Date: DECEMBER, 1992
Model: ALL
Subject:
NO HEAT/MPI FAULT CODE 21 (COOLANT TEMPERATURE SENSOR)
If the coolant thermostat sticks open, the engine may not reach proper operating temperature. This will result in low or no heat from the heater and it may
set a MPI fault code 21, Coolant Temperature Sensor.
The code will be set because the ECU will determine that the engine coolant has not reached proper operating temperature even though the engine has
been running.
If this occurs, verify coolant temperature is below specification and replace the thermostat if needed.
Refer to the shop manual for the proper specifications for the vehicle in question.
Make sure to erase the code after repairs are complete.
