What the P0134 code means?
The oxygen sensor reads the amount of oxygen and fuel that comes through the exhaust to make sure the
oxygen to fuel ratio is correct. The oxygen sensor sends that information to the power control module
(PCM).If there is an insufficient amount of oxygen in the exhaust, the power control module (PCM) will
decrease the amount of fuel that is being used by the motor. This is important because if there is an
insufficient amount of oxygen in the exhaust, the car will use more fuel and emit carbon monoxide into the
What causes the P0134 code?
Bad O2 (oxygen) sensor
Bad heater circuit in the O2 sensor
Wiring or connector to the sensor frayed / broken
Blown heater circuit fuse
Holes in the exhaust system
What are the symptoms of the P0134 code?
Check Engine Light will illuminate
Vehicle may idle or run rough
Decrease in fuel economy
Black smoke out of the exhaust and/or bad smelling exhaust
Common mistakes when diagnosing the P0134 code:
Technicians report replacement of oxygen sensors, when lean or rich engine conditions are the cause of
incorrect readings, is fairly common. Replacement of the incorrect oxygen sensor is also a possibility.
What repairs can fix the P0134 code?
1. The technician should use a scanner to validate the fault code. After the fault code has been validated,
it should be reset and a test drive should be performed. If the Check Engine Light returns with the same
fault code, an inspection should follow.
2. The wires and connectors should be inspected for any damage. If the wires and connectors are
damaged, they should be repaired or replaced. Reset fault code and test drive.
3. If the Check Engine Light comes on again and the technician gets the same code, the oxygen sensor will need to be replaced.
4. If the P0134 trouble code comes back after replacing the oxygen sensor, the exhaust pipe and heater fuse should be inspected to rule out possible damage of the two.