Air & Fuel Mixture ControlOBD2 Codes

P0133 – Meaning, Causes, Symptoms, & Fixes

What Does Code P0133 Mean?

  • P0133 definition: O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)
  • Issue Severity: MODERATE– Extended driving with this code can cause internal engine damage.
  • Repair Urgency: Get this code fixed as soon as possible.
  • Diagnosis: It is important to complete the entire diagnostic process when diagnosing the P0133 code. This DTC can be triggered by a faulty oxygen sensor, damaged wiring, or a leak in the intake manifold or exhaust system.

Find a Certified Shop

We've partnered with RepairPal to recommend trustworthy shops in your area. Enter your details to see certified shops near you that offer upfront estimates, guaranteed fair pricing, and a minimum 12-month, 12,000-mile warranty.

The O2 sensor (Bank 1, Sensor 1) is meant to communicate with the Engine Control Module (ECM) about the air to fuel ratio of the engine, and adjust it accordingly. This is done in order to limit the number of pollutants that your vehicle is emitting, and also control your car’s fuel consumption. Code P0133 is triggered when the voltage output that your O2 sensor is meant to send to your ECM does not change quick enough in relation to the air to fuel ratio when you press on the gas pedal.

P0133 Causes

  • Faulty O2 sensor (most common)
  • Faulty/Frayed wiring to the O2 sensor
  • Exhaust Leak
  • Engine Vacuum Leak
  • Dirty Mass Air Flow sensor

P0133 Symptoms*

  • Check Engine Light
  • Poor Fuel Economy
  • Excessive smoke from the exhaust
  • Rough running engine
  • Poor idle
  • Possible Stalling

*No noticeable adverse conditions in some cases

How Do I Fix Code P0133?

With a P0133 code, the first step is to get it properly diagnosed to figure out what is causing the malfunction in the downstream oxygen sensor system. Using the live data function of the FIXD sensor and app allows you to read and analyze engine data to properly diagnose a P0133 code.

If the sensors are all reading correctly and you’re not comfortable further diagnosing this issue at home, we recommend finding a RepairPal-certified shop to pinpoint the problem and give an accurate estimate for repairs. 

These shops can not only help you figure out what’s going wrong before you waste time and money on the wrong parts, but they also offer a minimum 12-month, 12,000-mile warranty and stand behind all their estimates with guaranteed fair pricing.

> Find a RepairPal Certified Shop Near You

How Much Does It Cost to Fix Code P0133?

If you take your car to a shop for diagnosis, most shops will start with an hour of “diag time” (the time spent in labor diagnosing your specific issue). Depending on the shop’s labor rate, this typically costs somewhere between $75-$150. Many, if not most, shops will apply this diagnosis fee to any required repairs if you have them perform the repairs for you. From there, a shop will be able to give you an accurate estimate for repairs to fix your P0133 code.

Right shop, right price

We've partnered with RepairPal to recommend certified and trustworthy shops in your local area. 

  • Upfront cost estimates
  • Minimum 12-month, 12,000-mile warranty
  • Fair price guarantee

Possible Repair Costs for P0133

When it comes to making repairs associated with the P0133 code, one or more of the below repairs may be needed to solve the underlying issue. For each possible repair, the estimated cost of repair includes the cost of the relevant parts and the cost of labor required to make the repair. 

  • Oxygen sensor $200-$300
  • Exhaust repair $100-$200 (if welded to repair)
  • Vacuum leak $100-$200

DIY Steps to Diagnose Code P0133

If you’d like to try to fix code P0133 at home without throwing money at parts, you’ll want to follow the steps below for proper diagnosis. Complete diagnosis may require some specialized equipment beyond what the FIXD Sensor can provide, but for the most part, this diagnosis and repair can be attempted by beginner DIYers. 

DIY difficulty level: Beginner

This repair can be attempted by beginner DIYers.

Tools/parts needed (our top picks from Amazon):


Scan your vehicle to verify P0133 is the only code present. If other codes are present, they must be addressed first.


Using the FIXD sensor and app, verify that all of the engine’s live data is within proper parameters. 


Conduct a visual inspection of wiring and connector at the O2 sensor for fraying or disconnection.


Check the Mass Air Flow sensor to make sure that it is not dirty and possibly putting out false readings which affect the O2 sensor. If it is dirty, clean it, clear your codes using the FIXD device, and re-scan to see if the code is still triggered.


Check for any exhaust or vacuum leaks. If there are any, fix them, clear your codes using the FIXD device, and re-scan to see if the code is still triggered.


If at this point the vehicle is still setting the same code, you may have a more serious problem with your car’s oxygen sensor system, and you should bring the vehicle to a certified shop to have further diagnostic work performed.  

Common P0133 diagnosis mistakes

The most common diagnosis mistake is not doing a visual inspection of the O2 sensor or the Mass Air Flow sensor before replacing it. Often times, the O2 sensor’s wiring is frayed or the Mass Air Flow sensor is dirty, which can both trigger Code P0133 to occur. Exhaust and Engine Vacuum Leaks can also cause P0133 to be triggered.

Still Need Help Fixing Code P0133?

If you’ve followed the steps above and are still experiencing issues with the oxygen sensor system and code P0133, please contact the FIXD Mechanic Hotline if you’re a FIXD Premium subscriber or find a RepairPal certified shop near you to get the right repairs at a fair price.


Lifelong automotive enthusiast with a soft spot for offroading. Wrencher turned writer, but I still love to tinker on just about anything with an engine. Dream car: tie between a ‘71 Hemi ‘Cuda and a ’91 GMC Syclone. #GirlDad #SaveTheManuals

Jeffrey N. Ross
Lifelong automotive enthusiast with a soft spot for offroading. Wrencher turned writer, but I still love to tinker on just about anything with an engine. Dream car: tie between a ‘71 Hemi ‘Cuda and a '91 GMC Syclone. #GirlDad #SaveTheManuals

You may also like


  1. where do I find my po133 sensor

    1. O2 sensor (bank 1, sensor 1) is located in front of the catalytic converter, towards the front of your engine.

      FIXD Team

      1. Hello i have a quesrion i have a crown Victoria ex police and,i have the code p0133 so i pit a new o2 sensor and,i delet the,code,but is still show me,the,code and,the,car feel run roughly and,i hear by the gas thank a whistle so i think is a vaccum there. So can u help me,please thank you

      2. I clean the mass air flow sensor too and,is the same code on i installed a new fuel pressure too

  2. Location of mass air flow sensor

    1. Mass airflow sensor will be in the air intake right after the air filter. Correct me if I’m wrong, FIXD.

  3. I will replace the 02 sensors bank 1 and 2.

  4. I have replaced the bank 1 and 2 02 sensors and also replaced the mass air flow sensor and the code and check engine light comes on now once the fuel gauge gets about a half a tank. I fill it up and it goes away until half a tank again.

    1. Mine does the same thing. It appears like there is a vacuum leak in the line from the fuel tank to the charcoal canister, or vacuum source to the fuel tank. I am told a smoke test at a repair shop is required to find the leak.

      1. I have exactly the same problem as Art has. Plus, I get kinda “drum” noise from the fuel tank as if something is blowing air on a closed circuit piece of cardboard. I figured when I open the gas tank lid, soda can effect pops up as if there was some pressure that was released and then noise goes away.

        I have replaced O2 sensor, and now converter as well.

        Don is right. There is most likely a vacuum link. My fuel consumption is exorbitant, hardly 18-19 mpg combined when it is supposed to be 22/37 mpg for my fusion.

        How did you perform the smoke test, and what was the remedy? Any help would be appreciated

      2. I have a 2004 Hyundai Sonata code p0133 where is the O2 sensor location bank 1 sensor 1 on my vehicle

  5. How much do I charge to replace the sensors

  6. Does FIXD work on different vehicles

Leave a reply

Your email address will not be published.