DTC P0134: Ho2S (Front) Circuit, No Activity Detected: 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 front HO2S signal voltage does not exceed .55 volt for 120 seconds after engine coolant temperature has reached more than 158°F (70°C) and engine speed is more than 1500 RPM. PCM monitoring is performed during Drive Mode 3 - HO2S, HO2S heater & TWC repair verification. See DRIVE MODES under SELF-DIAGNOSTIC SYSTEM. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are:

Engine malfunction.
Exhaust system leak.
Front HO2S deterioration or malfunction.
Low engine compression.
Open or short circuit between front HO2S and PCM.