DTC P0133: Ho2S (Front) Circuit, Slow Response: Condition

WARNING: This page is about a different car, the 2002 Mazda Protege5 and 2002 Mazda Protege. However, it is still accessible from the selected car via links, so may be relevant.

DTC is set when lean-to-rich and rich-to-lean average response time during HO2S inversion cycle period is slow. If response time exceeds threshold, PCM determines HO2S circuit has malfunction. PCM monitoring is performed during Drive Mode 3 - HO2S, HO2S heater & TWC repair verification. See DRIVE MODES under SELF-DIAGNOSTIC SYSTEM. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are:

Engine malfunction.
Exhaust system leak.
Front HO2S deterioration.
Front HO2S heater malfunction.
Fuel filter plugged or restricted.
Fuel leak at fuel line or return line.
Fuel pressure regulator malfunction.
Fuel pump malfunction.
Low engine compression.
Pressure Regulator Control (PRC) solenoid valve malfunction.
Purge solenoid hoses improperly connected.
Purge solenoid valve malfunction.