Diagnostic Aids

Perform this test when instructed during QUICK TEST or if directed by other test procedures. Only use this test to diagnose the following:

• HO2S & Sensor Connection
• Fuel Injector &/Or Fuel Injector Circuits
• Vacuum Systems
• Harness Circuits (HO2S, HO2S GND, INJ 1-10, VPWR & SIG RTN)
• Powertrain Control Module (PCM)

To prevent replacement of good components, be aware the following non-EEC areas may be cause of driveability concerns:

• Ignition System
• Faulty Evaporative Emission System
• EGR &/Or PCV System
• Air Intake System
• Engine Oil Contamination
• Fuel System
• Exhaust System Leaks Or Restriction
• Engine Cooling System

Fig 1: Locating HO2S (4-Cylinder)

Courtesy of FORD MOTOR CO.

Fig 2: Locating HO2S (V6 Or V8 With Dual Exhaust)

Courtesy of FORD MOTOR CO.

Fig 3: Locating HO2S (V6 Or V8 With Single Exhaust)

Courtesy of FORD MOTOR CO.

Fig 4: Identifying HO2S Connector Terminals

Courtesy of FORD MOTOR CO.