Test NTC-10A: Checking Oxygen Sensor Switching
NOTE:
Perform TEST NTC-1A or TEST NTC-9A
before proceeding.
WARNING:
High fuel pressure may be present in fuel lines. Open fuel system with caution. See FUEL SYSTEM PRESSURE RELEASE .
NOTE:
During first step, observe downstream O2S voltage does not switch like upstream O2S voltage.
- Start engine. Allow engine to reach normal operating temperature of 180°F (82°C). Using scan tool, read O2S signal voltages for 10 or more seconds. If O2S signal voltages are switching normally, O2 sensors are functioning normally. Test is complete. If O2S signal voltages are not switching normally, go to next step.
- If upstream O2S state is locked on LEAN, go to TEST NTC-10B . If upstream O2S state is not locked on LEAN, turn ignition off. Release fuel pressure. Install a fuel pressure gauge to fuel rail. Turn ignition on. Using scan tool, actuate ASD fuel system test. Allow fuel pressure gauge to stabilize for one minute. Go to next step.
- Using scan tool, stop ASD fuel system actuation. Observe fuel pressure gauge for one minute. If fuel pressure is less than 10 psi (70 kPa), replace leaking injector(s) as necessary. Perform TEST VER-2A . If fuel pressure is 10 psi (7 kPa) or more, go to next step.
- Inspect air filter and inlet ducts for restrictions. If restrictions are present, clean inlet system as necessary. Perform TEST VER-2A . If restrictions are not present, go to TEST NTC-13A .