H - Testing Notes

Heated Oxygen Sensor:

DESCRIPTION
The Heated Oxygen Sensor (HO2S) reacts with the oxygen in the exhaust gases and generates a voltage based on this reaction. A low voltage indicates too much oxygen or a lean condition. A high voltage indicates not enough oxygen or a rich condition. The fuel injector is a typical on/off device. The amount of fuel delivered is determined by how long the injector is held open.

NOTE
You should enter this Pinpoint Test only when you have been directed here from Diagnostic Routines, or Pinpoint Test S.

REMEMBER
To prevent the replacement of good components, be aware that the following non-Electronic Engine Controls (EEC) areas may be at fault:

- Ignition System

- Evaporative Emission (EVAP) System

- Positive Crankcase Ventilation System

- Secondary Air Injection System

- Exhaust Gas Recirculation (EGR) System

- Air Intake System/Filter

- Fuel and Engine Oil Contamination

- Electrical System

- Fuel System (i.e. Fuel Filter Pump Pressure)

- Intake Manifold, Supercharger, charge Air Cooler Leaks

- Exhaust Manifold System Leak/Plugged

- Engine Cooling System

- Base Engine (i.e. cam timing, compression)

This Pinpoint Test is intended to diagnose only the following:

- HO2S/Heater

- HO2S Connection

- Vacuum Systems

- Fuel Injector

- Powertrain Control Module (PCM)

- Harness Circuits: HO2S GND, HO2S, INJ. 1-8, VPWR and SIG RTN