Air & Fuel Mixture ControlOBD2 Codes

P0136 – Meaning, Causes, Symptoms, & Fixes

What Does Code P0136 Mean?

  • P0136 definition: H02S2 Heater Control Circuit Low (Bank 2, Sensor 2)
  • 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 P0136 code. This DTC can be triggered by a faulty oxygen sensor, damaged wiring, or a leak in the intake manifold or exhaust system.

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Your car has oxygen (O2) sensors that measure the amount of oxygen present in your exhaust. Based on the measurements taken, the O2 sensor will fluctuate between a high(rich) and low(lean) voltage reading. Your Engine Control Module (ECM) uses the voltage levels provided by your O2 sensors to regulate your engine’s fuel injector pulse. If you are seeing code P0136, it means that the O2 sensor behind your catalytic converter on bank 1 is malfunctioning.

P0136 Causes

  • Faulty Bank 1 O2 sensor 2
  • Exhaust leak in front of sensor 2
  • Intake Leak
  • Corrosion in connecter
  • Frayed or broken wiring

P0136 Symptoms*

  • Check Engine Light
  • Decrease in MPG
  • Increased tailpipe emissions

*No noticeable adverse conditions in some cases

How Do I Fix Code P0136?

With a P0136 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 P0136 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 P0136?

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 P0136 code.

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Possible Repair Costs for P0136

When it comes to making repairs associated with the P0136 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 P0136

If you’d like to try to fix code P0136 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 P0136 is the only code present. If other codes are present, they must be addressed first.


Note if the O2 sensor is rapidly or slowly switching from low to high voltage. This could indicate a faulty O2 sensor.


Check for any broken or shorted wiring in relation to the O2 sensor. If there is any broken or shorted wiring, make sure to repair or replace it.


Check for any vacuum leaks in the engine or any holes in the exhaust that could lead to air escaping from the engine. Repair any leaks or holes you find.


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 P0136 diagnosis mistakes

Replacing the O2 sensor without checking for any intake or exhaust leaks or loose connections.

Still Need Help Fixing Code P0136?

If you’ve followed the steps above and are still experiencing issues with the oxygen sensor system and code P0136, 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

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  1. Needed diagnostic info for a similar (yet different) P0137 CEL code

    1. No problem Ryan! Here is a link for our article on Check Engine Light code P0137.

      1. How much to replace all O2 sensor for 1999 ml 320 ?? Parts and labor ??

        1. Hi, just wanted to ask how do I Scan codes and document freeze frame data then clear codes to verify failure. And how do I find out if the o2 sensor is slowly switching to high or low voltage?

        2. How to replace P0136 sonsor is failed and light engen

      2. Have p0134 code can it be catalytic converter or fuel pressure..pit fuel pressure gauge on and it goes around twice and stats their..pit a bypass on fuel gauge and let has go into engine and into a 5 gal bucket and then had 55 to 60 lbs of pressire

  2. My car was running fine ,but check engine light was ,on b4 I got the car some one had a home made cold air intake on it ,I replaced it the other day with the proper one ,no air leaks etc,its properly but afterwards, car idles norm but will shut off sometimes when slowing and hesitating sometimes in 5th gear when at cruising speed 40/45 mph had it code checked and got PO137, OXY SENSOR BANK1 SENSOR 2 LOW VOLT, PO138 OXY SENSOR BANK 1 SENSOR 2 HIGH VOLT ,P1235 ,AND PO300 ,

  3. Please show me where is located the catalytic 02 sensor for my Dodge Ram 1500 2003 4.7 engine. Also need to now where is located the vacuum.

  4. I’m getting this code, I have the FIXD app and device, I cleared the code, will I fail emissions test with this code popping up?

    1. Hello Brian,

      If the code is emissions related, it cannot be cleared by a scanner. The light will come back on if the problem persists. It is recommended to have this code repaired as soon as possible as continuing to drive could risk greater damage to your vehicle’s engine.

      I hope this helps!

  5. I had a dirty mass air flow sensor that caused this error.

    1. which code are you referring to :p0136 or p0137? My highlander has a new rear oxygen sensor and I still got p0136. thanks,

  6. Where is the O2 sensor located on my Ford Escape 2003?
    Many thanks

  7. Where are the 4 O2 sensors located on a 2013 Nissan Pathfinder?

  8. PO137 Bank 1 SENSOR

  9. FIXD helped me with my engine trouble

    1. Thank you so much for using FIXD, Leo! We are so happy we were able to help you with your engine trouble. Happy and safe driving 🙂

  10. What would you consider “a short period of time…” Vs “…an elongated period of time…”?

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