Neon L4-2.0L SOHC (1995)
WHEN MONITORED:
With the engine running in closed loop and the coolant temperature above 170°F.
SET CONDITION:
The oxygen sensor signal voltage stays between 0.5 and 1.2 volts without toggling for at least 8 minutes.
THEORY OF OPERATION:
The oxygen sensor is a voltage generating device. The PCM receives exhaust gas information from the O2 sensor. The sensor detects exhaust gas
content by a galvanic reation within the sensor that produces a voltage. After measuring the amount of oxygen in the exhaust gases, the oxygen
sensor tells the PCM how well its output signal is controlling the air/fuel ratio.
Variations in the signals from the O2 sensor serve as air/fuel ratio indicators. Changes in the sensor signal occur because the air/fuel ratio is
constantly changing.
-
When the oxygen content is low (rich mixture) the voltage signal will be approximately 1 volt.
-
When oxygen content is high (lean mixture) the voltage signal will be low, approximately 0.1 volt.
POSSIBLE CAUSES:
-
High fuel pressure
-
Other engine sensor calibrations
-
Ignition system failure
-
O2 sensor failure
-
Mechanical engine problem
O2S Stays Below Center (Lean)
NAME OF CODE:
O2S Stays Below Center (Lean)
WHEN MONITORED:
With the engine running in closed loop and the coolant temperature above 170°F.
SET CONDITION:
The oxygen sensor signal voltage stays below 0.5 without toggling for at least 8 minutes.
THEORY OF OPERATION:
The oxygen sensor is a voltage generating device. The PCM receives exhaust gas information from the O2 sensor. The sensor detects exhaust gas
content by a galvanic reation within the sensor that produces a voltage. After measuring the amount of oxygen in the exhaust gases, the oxygen
sensor tells the PCM how well its output signal is controlling the air/fuel ratio.
Variations in the signals from the O2 sensor serve as air/fuel ratio indicators. Changes in the sensor signal occur because the air/fuel ratio is
constantly changing.
-
When the oxygen content is low (rich mixture) the voltage signal will be approximately 1 volt.
-
When oxygen content is high (lean mixture) the voltage signal will be low, approximately 0.1 volt.
POSSIBLE CAUSES:
-
Low fuel pressure
-
Vacuum Leak
-
Other engine sensor calibrations
-
Ignition system failure
-
O2 sensor failure
-
Mechanical engine problem
Upstream O2 Sensor Heater Failure
NAME OF CODE:
Upstream O2S Heater Failure
WHEN MONITORED:
With the ignition key OFF, after the engine cools down.
SET CONDITION:
No sensor output signal is received when the Powertrain Control Module (PCM) powers up the sensor heater.
THEORY OF OPERATION:
The upstream oxygen sensor is a voltage generating device. The PCM receives exhaust gas information from this O2 sensor. The sensor detects
exhaust gas content by a galvanic reaction within the sensor that produces a voltage. After measuring the amount of oxygen in the exhaust gases,
