Idle HC/Co Concentration Check

WARNING: This page is about a different car, the 2002 Saturn LW300 and 2002 Saturn L300. However, it is still accessible from the selected car via links, so may be relevant.

IMPORTANT: This check is used only to assist with idle HC/CO Diagnostics.

Initial Conditions:
- Engine must reach normal operating temperature.
- Air cleaner installed.
- All pipes and hoses of air induction system connected.
- All vacuum lines properly connected.
- All fuel system wiring connections fully plugged.
- Transmission in P (Park) or N (Neutral) range.
- Tachometer and HC/CO meter calibrated and in hand.
Run engine at 2500 RPM for approximately two minutes.
Insert HC/CO meter testing probe into intermediate pipe at least 40 cm (16 in.).
Check HC/CO concentration at idle.
IMPORTANT: Wait at least 1 minute before measuring to allow concentration to stabilize. Complete measuring within 3 minutes. If HC/CO concentration does not conform, see HC/CO DIAGNOSTIC CHART for possible causes.