P0135 code

After get battery replacement service in GM dealer, I got 'Service Engine Soon' light on dash board with code p0135 on my montana. Before that my car have not had any problem.
How to fix it? thanks any comment and help! except following comment:
Possible causes
- Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit fuse
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit open shorted to ground
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 1 circuit poor electrical connection
- Faulty Powertrain Control Module (PCM)
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Tech notes
The code means that there is a problem with the heater element circuit of the heated oxygen sensor. The control module monitors how long it take the sensor to warm up and start sending an adequate signal. The code is triggered when the sensor is taking too long to warm up. Before replacing the sensor, check for the condition of the heated oxygen sensor fuse and connectors. If the sensor and connector are OK, replacing the O2 Sensor 1 usually takes care of the problem
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When is the code detected?
If the Powertrain Control Module (PCM) detects that the process took too much time for the HO2S to enter into normal operating range, a DTC sets. The time the process takes the HO2S to reach operating temperature is based on the amount of air that flows into the engine.
Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Possible higher than usual fuel Consumption
P0135 PONTIAC Description
The Powertrain Control Module (PCM) supplies a bias voltage (approximately 450 mV) on the Heated Oxygen Sensor (HO2S) signal high and low circuits. When you turn the ignition to the ON position, battery voltage is supplied to the HO2S heater. As the heater reaches the operating temperature, the HO2S voltage responds by changing from a bias voltage range to the normal operation. Typically, as the HO2S reaches the operating temperature, the HO2S voltage goes from a bias voltage to a voltage below 300 mV. Depending on the exhaust gas content, it is possible for the HO2S voltage to go above 450 mV.
The PCM runs the heater test only on a cold start (depends on the cumulative air flow) and only once an ignition cycle. When you start the engine the PCM monitors the HO2S voltage. When the HO2S voltage goes above or below the bias range threshold, the PCM determines how much time it took.
PONTIAC Technical Service Bulletins for P0135 code
2004 PONTIAC GTO ENGINE AND ENGINE COOLING:ENGINE Details
2004 PONTIAC GTO 061000 ENGINE AND ENGINE COOLING:ENGINE Details
2002 PONTIAC SUNFIRE ELECTRICAL SYSTEM Details
2002 PONTIAC SUNFIRE 110000 ELECTRICAL SYSTEM Details

Read more: http://helpforcars.net/obd_codes/p0135_pontiac.html#ixzz2yJBshFSV