Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSPLYMOUTH1984HORIZON BASE, 1.6 AREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 7 (ENGINE CONTROLS - TESTS W/CODES - 2.2L)SELF-DIAGNOSTIC TESTSTEST NTC-7A - CHECKING OXYGEN (O2) SENSOR SWITCHING
1984 Plymouth Horizon Base, 1.6 A
Test NTC-7A - Checking Oxygen (O2) Sensor Switching
1984 Plymouth Horizon Base, 1.6 ASECTION Test NTC-7A - Checking Oxygen (O2) Sensor Switching
WARNING: This page is about a different car, the 1994 Plymouth Sundance and 1994 Dodge Shadow. However, it is still accessible from the selected car via links, so may be relevant.
WARNING:
High fuel pressure may be present in fuel lines. Open fuel system with caution. See FUEL PRESSURE RELEASE
procedure.
- Allow engine to reach normal operating temperature. Using DRB, read O2 sensor state. If O2 sensor state is switching, system is functioning properly. Test is complete. If O2 sensor state is not switching, check if O2 sensor is locked on lean. If O2 sensor is locked on lean, go to TEST NTC-7B. If O2 sensor is not locked on lean, turn engine off.
- Release fuel pressure. Install fuel pressure gauge in fuel supply line. Turn ignition on. Using DRB, actuate fuel system. Allow fuel pressure gauge to stabilize to normal fuel pressure. Stop fuel system actuation. Monitor fuel pressure gauge for one minute.
- If fuel pressure gauge reading drops more than 10 psi (.7 kg/cm2 ), replace leaking injector(s) or "O" rings as necessary. Perform TEST VER-2 . If fuel pressure gauge reading does not drop more than 10 psi (.7 kg/cm2 ), go to next step.
- Inspect air cleaner and inlet ducts for restriction(s). Repair as necessary. Perform TEST VER-2. If no restrictions are present, go to TEST NTC-15A .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.