Oxygen sensor inversion not detected

P1169 - upstream of catalyst (middle) / rear (RH) bank

P1170 - upstream of catalyst (front) / rear (RH) bank

P1173 - upstream of catalyst (front) / front (LH) bank

Emissions Equipment Information

Three o² sensor system (KL engine with one catalytic converter) - A front sensor is positioned on the LH bank and a middle sensor is positioned on the RH bank upstream of the catalyst for closed loop fuel control.  A rear sensor is mounted downstream of the catalyst to monitor its efficiency.

Four o² sensor system (KJ / KL engine with three catalytic converters) - Front sensors are mounted upstream of the RH and LH warm-up three-way catalyst (WU-TWC) for closed loop fuel control.  Rear sensors are mounted downstream of the WU-TWCs to monitor their efficiency.

Detection Conditions

• If the input voltage from the oxygen sensor remains below or above 0.45V for longer than 43 seconds, the ECU determines that there is no oxygen sensor inversion under the following monitoring conditions:
  • engine speed is above 1500 rpm
  • engine coolant temperature is above 80 degrees C

Diagnostic Support Notes

• This is an continuous monitor (CCM)
• The check engine indicator illuminates if the ECU detects the above malfunction condition in two consecutive drive cycle
• PENDING CODE is available
• FREEZE FRAME DATA is available
• DTC is stored in ECU memory

Possible Causes

• Oxygen sensor malfunction
• Oxygen sensor heater circuit malfunction
• Fuel injector malfunction
• Fuel pressure regulator malfunction
• Fuel pump malfunction
• Fuel delivery hose restriction
• Fuel filter restriction
• Fuel return hose restriction or leakage
• Intake air suction or leakage
• PCV valve malfunction
• Purge solenoid valve malfunction
• Purge solenoid hoses misrouted
• Ignition coil malfunction
• Insufficient compression
• Engine malfunction

[P1169 / P1170 / P1173 - From 2002 Mazda Millenia factory service manual]