P0133: Oxygen Sensor Circuit Slow Response

When the check engine light comes on, it can indicate a wide variety of potential issues. If you're using an OBD-II scanner to zero in on the specific problem, your next question may be, how do I fix trouble code P0133?

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What Does the Code P0133 Mean?

The code P0133 indicates your vehicle’s oxygen sensor is having a problem. This sensor monitors how much oxygen comes out of the engine and transmits this information to your vehicle’s computer. Based on this input, the computer calibrates the amount of fuel going into the engine to maintain the optimal ratio between air and fuel. This ability to perform this calibration accurately is important to minimize fuel consumption and pollutant emission. When the oxygen sensor is not performing well, the air-fuel ratio may not be optimal, possibly resulting in excess fuel usage and increased pollution.

The oxygen sensor essentially works by transmitting a voltage reading to the computer. This reading changes every time the air-fuel ratio changes, which in turn changes every time the driver presses the pedal. If you get an OBD-II scanner error code P0133 problem, this indicates your car’s computer is not receiving the sensor’s signals quickly enough.

What Are the Symptoms of Oxygen Sensor Circuit Issues?

Because the oxygen sensor is an important component of fuel regulation, problems in this area can be serious. You may notice signs such as:

  • Decreased gas mileage
  • Misfiring or stalling engine
  • Worsening engine performance

The last two symptoms usually only tend to arise in a noticeable way when the problem has been allowed to persist for some time. Failing an emissions test can also stem from issues with this sensor. Keep in mind that while the P0133 code typically stems from a problem with the oxygen sensor, there may also be another important issue causing the delayed response that gives rise to the code.

What Can Be Done To Fix P0133?

There is always the possibility that the code will go away if you reset it. If it does come back, the most likely cause is that the oxygen sensor is not working correctly. The straightforward solution to a malfunctioning oxygen sensor is to replace it. However, code P0133 can also point to other issues that could cause slowness in transmitting the voltage reading from the sensor. If the sensor itself is working properly, the error code could stem from:

1. Soot or oil buildup on the oxygen sensor

This can clog the sensor’s ports and prevent the sensor from taking measurements. Cleaning away any buildup can take care of this issue.

2. Faulty wiring

If the wiring connecting the sensor to other components is frayed, damaged or saturated with oil, signal transmission can be affected. Checking the wiring and replacing, cleaning or fixing problem areas is the right fix for this situation.

3. Leaking vacuum or intake manifold line

Leaks from either of these lines can throw off your sensor’s voltage readings to the point where an OBD-II scanner error code P0133 problem arises. In this case, there is nothing wrong with the sensor and fixing the leaking line should get the readings back to normal.

4. Incorrect fuel pressure

This also can result in erratic oxygen sensor readings. Incorrect fuel pressure can result from a number of causes, including issues with the fuel regulator, filter, pump and other components. It can also cause a number of serious problems with your vehicle and should be addressed promptly.

5. Dirty or malfunctioning mass air flow sensor

Checking the mass air flow sensor and correcting any issues can get rid of a P0133 error code.

Using an OBD-II scanner can give you more specific information about why your check engine light is on. While a P0133 code does not typically point to problems that seriously compromise safety or driveability, it is important to take care of these issues promptly. Even when the problem is fairly minor, addressing it quickly prevents it from snowballing and beginning to affect other components. You can get the parts you need at your local AutoZone Store. If the job is too big for you, seek out one of our Preferred Shops to help you do the job.

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