Circuit Description

Powertrain Control Module (PCM) supplies about.45 volt to Heated Oxygen Sensor 1 (HO2S 1). The HO2S 1 generates a voltage that varies from about one volt when exhaust is rich to about.10 volt when exhaust is lean. PCM monitors and stores sensor voltage information and evaluates the voltage samples to determine amount of time sensor voltage is out of range. If PCM detects HO2S 1 voltage remains at or near.45 volt for an extended period of time, DTC P0134 will set.

For duplication of DTC, ensure:

• DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0200, P0335, P0336, P0351-P0358 and P1258 are not set.
• Ignition voltage is greater than 9 volts.
• AIR, EGR and catalyst diagnostics are not active.
• Fuel system is operating in closed-loop.
• Engine run time is greater than 70 seconds.