P0133 Code – Meaning, Causes, Symptoms (& How To Fix)

You know how many parts work together to keep the car engine running as it should. When the Check Engine Light comes on, a quick scan can show us precisely what’s wrong. However, some DTCs have multiple causes, such as the P0133 code.

We show you what the P0133 trouble code might mean, so you can get it fixed quickly. We also give you some of the top causes and reveal its top symptoms.

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Code P0133 Definition

P0133 – Oxygen Sensor Circuit Slow Response (Bank1, Sensor1)

What Does the P0133 Code Mean?

P0133 shows that there is a problem with the O2 sensor (Bank 1, Sensor 1). This sensor is needed to communicate with the car’s Engine Control Module (ECM) in relation to the air/fuel ratio. When the voltage output of the O2 sensor doesn’t line up with normal parameters, the code gets set.

This voltage is monitored as you push on the accelerator pedal. When that happens, the voltage should change. If it doesn’t, there could be something wrong with the O2 sensor or other components.

P0133 Trouble Code Symptoms

In many cases, drivers can have the P0133 code set in the computer without any drivability issues. Instead, all that is seen is the Check Engine Light on the dashboard.

Here are some symptoms that could possibly exist, especially as the problem gets worse.

Check Engine Light
Reduced fuel economy
Exhaust smoke
Engine running rough
Unusual idle
Stalled engine

Causes of the P0133 Code

It would seem most obvious that the problem is the O2 sensor, and that’s probably right. However, there are several causes that can lead to the P0133 code.

Here are the most common causes of the P0133 trouble code.

How Serious is the P0133 Code?

Medium – This code probably won’t lead to disastrous problems right away. You could drive your vehicle for a short time if there are no issues that could cause an accident. However, there are a few points to consider.

If the O2 sensor isn’t regulating the air-fuel ratio, there could be more pollutants being pumped into the air. It could also lead to some engine damage if you continue driving with an imbalanced ratio, which is why you should have it repaired as soon as you can.

What Repairs Can Fix the P0133 Code?

After a complete diagnostic scan and inspection, you should be able to figure out what’s wrong with the system. Here are a few of the top fixes that relate to this code.

Clean or replace the O2 sensor
Repair O2 sensor wiring
Repair exhaust leak
Replace mass air flow sensor
Repair vacuum leak

Common P0133 Diagnosis Mistakes

In many cases, this trouble code is related to the O2 sensor, so drivers will go ahead and replace it. The problem is that the sensor itself might not be defective, so you would replace the part unnecessarily.

Instead, you must make sure that you perform an inspection of the sensor and its wiring first. It’s possible that you can repair some of the wiring or clean the sensor, which will save you money on the sensor itself.

How to Diagnose the P0133 Trouble Code

Even if you aren’t a professional mechanic, you can troubleshoot the P0133 code as if you were. The majority of mechanics would tell you to follow these steps.

Run the code scanner to see what shows up. If anything other than P0133 shows up, make sure you address that first.
Reset the codes if there are too many and drive the vehicle until the Check Engine Light comes on. With the freeze frame data, you will have a better idea of what’s happening.
Inspect the O2 sensor. You want to look closely at the connector and wiring to see if there’s a visible defect. If the sensor needs to be cleaned, you can do that in a matter of minutes. Otherwise, go ahead and replace any defective wiring you spot.
Inspect the mass air flow sensor. Again, look closely at the connector and wiring to see if there’s a visible defect. Clean the sensor if needed. Otherwise, go ahead and replace any defective wiring you spot.
Check for an exhaust or vacuum leak. You can find guidelines for these procedures in your vehicle service manual.
If nothing else seems to be wrong, go ahead and try a new O2 sensor. Hopefully, the code goes away and your problem is resolved.

If none of these steps help, it’s best to visit your neighborhood mechanic for more support. The professional auto repair shop will have more advanced equipment to give you a better diagnosis.

Estimated P0133 Repair Cost

Understanding the various fixes that might repair the P0133 trouble code, you want to know what you are going to spend. We have estimated some of the prices for labor and parts based on what you find through the complete diagnosis.

New O2 sensor – $125-$600
New O2 sensor wiring – $50-$750
Repair exhaust leak – $100-$650
Replace mass air flow sensor – $75-$450
Repair vacuum leak – $125-$1250

Mechanics Tips about the P0133 Code

This trouble code shows you there is a problem with the Oxygen Sensor located at bank 1 sensor 1. If there’s a problem with one of the other oxygen sensors, you will see a different code. Here are two you might get.

P0139 –O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)
P0145 –O2 Sensor Circuit Slow Response (Bank 1 Sensor 3)