Error P0134 – how to fix?

P0134 Code Definition

Diagnostic trouble code P0134 is an indication that there is a problem with the oxygen sensor located in front of the catalytic converter and on the engine bank that houses cylinder # 1.

What does the code P0134 mean

• The oxygen sensor reads the amount of oxygen and fuel coming from the exhaust system to make sure the oxygen / fuel ratio is correct. The oxygen sensor sends this information to the power control module (PCM).
• If there is insufficient oxygen in the exhaust gas, the Power Control Module (PCM) will reduce the amount of fuel used by the engine. This is important because if there is not enough oxygen in the exhaust gas, the car uses more fuel and emits carbon monoxide into the atmosphere.
• If the amount of fuel in the exhaust gas is insufficient, the power control module (PCM) increases the amount of fuel used by the engine. This is important because if there is not enough fuel in the exhaust gas, the car will emit hydrocarbons and nitrogen oxides into the air.

What causes the code P0134?

The millivolt reading from a properly functioning oxygen sensor is moving up and down. When the power control module (PCM) detects that the millivolt oxygen sensor is stopped and not working properly, it will cause trouble code P0134. This fault code can be caused by the following factors:

• Heater circuit damaged.
• Damaged or disconnected oxygen sensor cable.
• Corrosion at joints
• Vacuum leak in the engine
• Faulty Power Control Module (PCM)

What are the symptoms of the P0134 code?

There are several things that can occur with fault code P0134:

• The Check Engine light on the dashboard may come on and the engine may fail.
• You may experience the feeling that your car is running low or idling.
• There may also be a smell of something like rotten eggs and / or black smoke from the exhalation.
• There are times when the driver will not notice any of these symptoms other than the warning light for the engine, but this is rare.

How does the mechanic diagnose the P0134 code?

The technician will use an OBD-II scanner to diagnose the P0134 code. You must capture the freeze frame data to determine when the code was first set. At this point, delete the code and check the vehicle.

During the test drive, the vehicle should reach normal operating temperature to verify that the code reappears. If the fault code returns, check the wiring to the oxygen sensor and the ground. During the inspection, the technician will look for cracks and corrosion. Live data should be observed to determine if millivolt valves are going from low to high.

The oxygen sensor should also be inspected to determine if it has power and is receiving the correct signal voltage from the Power Control Module (PCM).

The most common errors when diagnosing the code P0134

A common mistake made when diagnosing fault code P0134 is to assume that the oxygen sensor is the first thing to be replaced without considering the alternatives.

Sometimes the oxygen sensor itself is not the problem, and there are other things that can prevent the oxygen sensor from working, such as the oxygen sensor wiring. Before replacing the oxygen sensor, check the wiring and rule out the cause.

How serious is the P0134 code?

Fault code P0134 is unlikely to prevent the vehicle from being operated as it should start and run, but drivers may experience a lack of power.

Driving with error code P0134 may damage the catalytic converter, but it requires a long period of time. The most shocking thing about this fault code is that fuel economy drop is common, so the car will burn fuel at a higher rate. For this reason, it is important for the technician to diagnose this code as well as make any necessary repairs as soon as possible.

What repairs can fix the code P0134?

1. The technician should use a scanner to validate the error code. After confirming the fault code, delete it and carry out a test drive. If the check engine light reappears with the same fault code, a check must be carried out.
2. Cables and connectors should be checked for damage. If cables and connectors are damaged, they must be repaired or replaced. Reset the error code and carry out a road test.
3. If the engine light comes on again and the technician receives the same code, the oxygen sensor will need to be replaced.
4. If error code P0134 reappears after replacing the oxygen sensor, check the exhaust pipe and the heater fuse for possible damage to both.

Additional notes regarding the P0134 code

Most often it is necessary to replace the oxygen sensor with a new one. Before replacing the oxygen sensor, however, a problem with the wiring and connectors must be ruled out.

It is important to reset the error code and test the vehicle after repairing or replacing any cables, connectors or oxygen sensor to see if the code reoccurs before moving on to the next possible problem.

If the fault code still appears after checking the wiring and / or connectors and replacing the oxygen sensor, there are a few less likely possibilities of obtaining this code. Some cars have a fuse for the oxygen sensor heating circuit and in this case, it is possible that the fuse has blown, although this is not common.

It is also possible that the exhaust pipe has holes or an excessive amount of rust. The last and least likely possibility of obtaining this code is that the Power Control Module (PCM) is faulty and needs to be replaced.