DTC 25

1. Confirm initial test conditions:
a. Engine at normal operating temperature.
b. Air cleaner installed.
c. All pipes and hoses of the air induction system connected.
d. All accessories turned OFF.
e. All vacuum lines properly connected.
f. EFI system wiring connectors tightly attached.
g. Ignition timing set correctly.
h. Transmission in N range.
i. Tachometer and HC/CO meter calibrated and installed on vehicle.
2. Start the engine and confirm that idle speed is within specifications.
3. Refer to OXYGEN SENSOR testing and check operational output.
4. If any abnormalities are detected, repair before continuing with test procedures.
5. Rev the engine to 2,500 rpm for approximately 2 minutes.
6. Allow the engine to return to idle and stabilize for at least 1 minute.
7. Check HC and CO concentrations with HC/CO meter.
8. If outside of State Regulated Specifications, refer to troubleshooting chart for possible causes.

Troubleshooting Chart: