Pre-Diagnostic Instructions

Before performing any engine performance, fuel economy or exhaust emission diagnostic procedures on the Throttle Body Fuel Injection System, perform all diagnosis which would apply to a vehicle not equipped with this system.

To verify proper operation of the system always begin diagnosis with the "Diagnostic Circuit Check".
- When performing the "Diagnostic Circuit Check" the drive wheels must be blocked.

On some engines, the oxygen sensor will cool off after only a short period of operation at idle, which will put the system into open loop operation.
- To restore closed loop, run the engine at part throttle for several minutes and accelerate from idle to part throttle a few times.