P0133: Oxygen Sensor Slow Response (Bank 1, Sensor 1)

What does the P0133 error code mean?

The P0133 check engine diagnostic trouble code stands for "Oxygen Sensor Slow Response (Bank 1, Sensor 1)." The presence of this code indicates that the powertrain control module is no longer receiving signals from the oxygen sensor located on bank 1, sensor 1, quickly or frequently enough for the car to run optimally. This code may also be present on certain vehicles if there is a failure on bank 1, sensor 2.

Why is this issue important?

Oxygen sensors in your car are sensors able to detect the oxygen content in the exhaust gases leaving the car's engine. These gases are read and transmitted to the car's powertrain control module. From there, the powertrain control module uses this information to regulate the amount of fuel injected into the engine before the air and fuel mixture inside the engine's cylinder is ignited by the spark plugs. Usually, the result is a check engine light and other symptoms of an engine running poorly, like rough idling.

Can I safely drive my car with this error code?

Depending on the severity of the fault, it may be possible to drive with a P0133 code. However, the code does not always indicate the severity of the issue, and you should avoid driving if possible. The delayed sensor response may cause poor fuel economy and slight performance issues. More importantly, if the air-fuel mixture becomes too rich (meaning there's too much fuel and not enough air) or too lean (meaning the opposite), it could lead to engine misfires or damage.

Common symptoms of the P0133 error code

• Illuminated check engine light
• Poor fuel economy
• Rough idling or hesitation
• Engine misfires
• Slower acceleration
• Black smoke from the exhaust

How is the P0133 error code diagnosed?

• Use an OBD-II scanner: Retrieve the P0133 code and check for any related trouble codes.
• Inspect the oxygen sensor wiring: Look for damaged, corroded or loose connections to the O2 sensor.
• Test the oxygen sensor: Use a multimeter or scan tool to measure the sensor's voltage fluctuations to determine if it responds slowly.
• Check for vacuum leaks: Unmetered air entering the engine can affect sensor readings and lead to the P0133 error code.
• Inspect the fuel system: Issues such as a clogged fuel injector or a faulty fuel pressure regulator can potentially impact the air-fuel mixture and trigger the error code.

How is the P0133 error code repaired?

• Replace the affected oxygen sensor.
• Repair or replace damaged wiring and connectors associated with the O2 sensor.
• Fix vacuum leaks that could be affecting sensor readings.
• Clean or replace clogged fuel injectors to restore the correct fuel ratio.

Related reading

On-board diagnostics (OBD-II) and diagnostic trouble codes are part of your car's self-diagnostic system. The five-character alphanumeric code identifies the part and problem. Check out Edmunds' growing database of diagnostic trouble code information here.