Diagnostic Trouble Code P0133

P0133 “O2 Sensor Circuit Slow Response Bank 1 Sensor 1”

What is code P0133?

Code P0133 stands for “O2 Sensor Circuit Slow Response Bank 1 Sensor 1”. This diagnostic trouble code can show up when there is a problem with one of the oxygen sensors in your vehicle that helps to regulate the air and fuel that enter the engine. Therefore, it is important to have a qualified technician diagnose the specific problem that caused the code to be stored in your vehicle’s computer.

Get this checked out soon by a CarAdvise shop, where the work will be guaranteed, and one of our expert techs will review any repair orders.

What does code P0133 mean?

When a technician reads a code P0133 on a diagnostic scan of your vehicle, the information indicates that there is something wrong with either an oxygen sensor (also called an O2 sensor) in bank 1, or an improper air to fuel ratio entering your engine. The Engine Control Module (ECM) has detected the problem and turned on the check engine light.

Your engine requires that a specific blend of air and fuel enter the combustion chambers in order for combustion to happen properly. When the air/fuel ratio is out of balance – whether because there is too much fuel (running “rich”) or too little fuel (running “lean”) – your engine will not function as it should. Harmful emissions increase, fuel economy drops, and a number of problems can affect drivability. Engine damage can also occur in some cases.

To help maintain a suitable air/fuel mixture, your vehicle is fitted with special sensors mounted in the exhaust system that measure the percentage of oxygen present in the exhaust gases. Data from these oxygen sensors is sent to the ECM where it is analyzed and used to adjust the air/fuel ratio accordingly. Bank 1 refers to the side of a “V” style engine (V6, V8, etc.) that contains cylinder number 1 (many engines have only one bank). Sensor 1 refers to the oxygen sensor placed upstream of the catalytic converter, the one that measures oxygen in the exhaust gases coming directly from the engine.

In order for the ECM to adjust the air/fuel mixture quickly, the oxygen sensor needs to respond quickly. Therefore, if the ECM detects that the response of this sensor is too slow, it will store code P0133 and turn on the check engine light.

What causes code P0133?

A number of causes can trigger a code P0133. That is why an accurate diagnosis is essential. Causes of this code include:

Most likely

Other possibilities

  • Damaged or deteriorated wiring to the oxygen sensor
  • Exhaust system leak
  • Low fuel pressure
  • Intake system leak or vacuum leak
  • Problem with the ECM

What symptoms are associated with this code?

Common signs associated with a code P0133 include the following:

  • The check engine light is on or flashing
  • Engine idles or runs roughly
  • Engine stalling
  • Reduced fuel economy
  • Black smoke from the tailpipe

How does a technician diagnose code P0133?

If a diagnostic scan of your vehicle indicates a code P0130, a technician will perform tests to pinpoint the problem. These tests include checking for any related trouble codes. The technician will also use the scan tool to read the live data from the oxygen sensors and make comparisons under various operating conditions. The wiring that leads to the sensor will also be inspected and tested, along with the sensor itself.

There are many issues that can lead to a code P0133, ranging from a bad sensor to a vacuum leak, coolant temperature sensor, carbon buildup, or dirty mass air flow sensor. Each of these can cause a problem with the data from the oxygen sensor. Therefore, a technician must inspect several vehicle components during diagnosis.

How serious is this code?

In some cases, a code P0133 will not cause any major drivability problems. It is common, however, that the problem will lead to a rough engine idle, hesitation, or stalling when you try to accelerate. You might have difficulty starting your vehicle. Fuel economy will suffer. Damage to the catalytic converter is possible in the long run due to excessive carbon buildup. At the very least, the presence of the check engine light will prevent your vehicle from passing an emissions test

Get this checked out soon by a CarAdvise shop, where the work will be guaranteed, and one of our expert techs will review any repair orders.


Related Diagnostic Trouble Codes

P0130 O2 Sensor Circuit Malfunction

P0131 O2 Sensor Circuit Low Voltage

P0132 O2 Sensor Circuit High Voltage

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