DTC P0134 - Right Front Heated Oxygen Sensor -Insufficient Activity Detected: Condition

WARNING: This page is about a different car, the 1997 Mazda Millenia. However, it is still accessible from the selected car via links, so may be relevant.

DTC is set when right front oxygen sensor signal voltage does not exceed .55 volt after engine is started, or stays below .55 volt for 99 seconds after engine has reached normal operating temperature. Engine speed at 1150 RPM or greater. Possible causes are:

Right front oxygen sensor.
Open or short circuit between terminal No. 3I on Engine Control Module (ECM) and terminal "A" (Red wire) on right front oxygen sensor.
Intake air system, fuel system and/or ignition system malfunction.