DTC P0134: Heated Oxygen Sensor No. 1 Circuit - No Activity Detected: Condition

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

DTC is set when Heated Oxygen Sensor (HO2S) No. 1 output voltage is too high or too low when vehicle is at normal operating temperature and is not operating under high load or high engine speed conditions. ECM continuously monitors this circuit. MIL is illuminated when ECM detects malfunction during 2 consecutive drive cycles. Possible causes are:

Short or open circuit between HO2S No. 1 and ECM.
HO2S No. 1 malfunction.
Fuel system malfunction.
Exhaust system leak.
Low fuel level.