DTC P0134: A/F Sensor (Sensor 1) Heater System Malfunction
Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle 2 minutes. If the code reappears, replace the sensor. If not, the sensor could simply need to be tightened. Check for poor connections or loose terminals too.
If the code doesn't reappear, I wouldn't sweat it