Mazda 2006 MX-5 Service Highlights page 33

P0133 Front HO2S circuit problem
• Front HO2S malfunction is detected by measuring of the average frequency of front HO2S signal, time required
to pass from rich to lean, time required to pass from lean to rich. If the average frequency of front HO2S signal
is more than the threshold value, the PCM determines that there is the front HO2S circuit problem.
MONITORING CONDITIONS
— HO2S heater, HO2S, and TWC Repair Verification Drive Mode
— Following conditions are met:
• Engine speed is 1,750—3,500 rpm.
• Charging efficiency is 25—63 % (at engine speed 2,500 rpm).
• Engine coolant temperature is above 70 °C {158 °F}
• Front HO2S heater monitor is completed.
• Fuel system loop status is closed loop fuel control.
P0134 Front HO2S no activity detected
• The PCM monitors the front HO2S element impedance when the following conditions are met. If the front
HO2S element impedance is 80 ohms or more, the PCM determines that front HO2S is not activated.
MONITORING CONDITIONS
— HO2S, HO2S heater and TWC Repair Verification Drive Mode
— Following conditions are met
• Time from engine start is above 30 s (ECT when engine start is 20 °C {68 °F}).
P0137 Rear HO2S circuit low input
• The PCM monitors input voltage from rear HO2S. If the input voltage from the rear HO2S is below 0.1 V for
35.2 s the PCM determines that circuit input is low.
MONITORING CONDITIONS
— HO2S, HO2S heater and TWC repair verification drive mode
— Following conditions are met.
• Engine speed is above 1,500 rpm.
• Engine coolant temperature is above 70 °C {158 °F}.
• Fuel injector control in rear HO2S closed loop control.
• The PCM monitors the input voltage from the rear HO2S when the following conditions are met. Under the
following monitoring conditions, if the input voltage from the rear HO2S does not even exceed 0.1 V though
the short term fuel trim is controlled up to 20.5 % for 9.6 s, the PCM determines that sensor circuit input is low.
MONITORING CONDITIONS
— HO2S, HO2S heater and TWC repair verification drive mode
— Following conditions are met for above 20.8 s.
• Engine speed is above 1,500 rpm.
• Engine coolant temperature is above 70 °C {158 °F}.
P0138 Rear HO2S circuit high input
• The PCM monitors input voltage from rear HO2S. If the input voltage from the rear HO2S sensor is above 1.2
V for 0.8 s, the PCM determines that circuit input is high.
P0139 Rear HO2S circuit problem
• The PCM monitors the rich (0.4 V) to lean (0.3 V) response time of the rear HO2S. The PCM measures the
response time when the following conditions are met. The PCM determines a rear HO2S response
deterioration malfunction when the measured response time is more than the threshold value (80 ms) five
consecutive times.
MONITORING CONDITIONS
— PCM Adaptive Memory Production, HO2S heater, HO2S, and TWC Repair Verification Drive Mode
— Following conditions are met:
• During deceleration fuel cut
• Engine speed is above 500 rpm.
• Engine coolant temperature is above 70 °C {158 °F}.
• Rear HO2S output voltage ia above 0.4 V.
• The PCM monitors for a time-out malfunction (when rear HO2S remains above 0.3 V for longer than a
specified period of time during fuel cut control). The PCM measures the amount of time from when the following
conditions are met until the rear HO2S output voltage drops below 0.3 V. The PCM determines a rear HO2S
time-out malfunction when the detected time is more than the threshold value (6 s) three consecutive times.
MONITORING CONDITIONS
— PCM Adaptive Memory Production, HO2S heater, HO2S, and TWC Repair Verification Drive Mode
— Following conditions are met:
• During deceleration fuel cut
• Engine speed is above 500 rpm.
• Engine coolant temperature is above 70 °C {158 °F}.
• Rear HO2S is activated (more than 0.55 V)
ON-BOARD DIAGNOSTIC
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