Hardening, shrinkage, or damage of both gaskets and O-rings after disassembly can reduce sealing performance.
Remove old gaskets and clean the sealing surfaces thoroughly so that no gasket material or other material remains.
Install the new gaskets and replace the used O-rings when re-assembling.

Force
Liquid Gasket, Non-permanent Locking AgentTachometer
The tachometer shows the engine
speed in revolutions per minute (r/min,
rpm).
On the right side of the tachometer
face is a portion called the “red zone�.
Engine r/min (rpm) in the red zone is
above maximum recommended engine
speed and is also above the range for
good performance.
...
Intake Air Temperature Sensor Resistance Inspection
Remove the intake air temperature sensor (see Intake Air
Temperature Sensor Removal).
Suspend the sensor [A] in a container of machine oil so
that the heat-sensitive portion is submerged.
Suspend a thermometer [B] with the heat-sensitive portion
[C] located in almost the same depth with ...
DFI Servicing Precautions
There are a number of important precautions that should
be followed servicing the DFI system.
This DFI system is designed to be used with a 12 V sealed
battery as its power source. Do not use any other battery
except for a 12 V sealed battery as a power source.
Do not reverse the battery ...