Air & Fuel Mixture ControlOBD2 Codes

P0134 – Meaning, Causes, Symptoms, & Fixes

Code P0134 Definition

O2 Sensor Circuit No Activity Detected (Bank 1, Sensor 1)

What Does P0134 Mean?

Code P0134 is triggered when your vehicle’s O2 sensor (bank 1, sensor 1) is malfunctioning. The Engine Control Module (ECM) detects that the Oxygen (O2) sensor is at a standstill and is not accurately reading the amount of oxygen in the exhaust. This error in the oxygen sensor causes the ECM to misread the amount of oxygen and fuel coming through the exhaust, which inhibits it from ensuring the optimal fuel ratio.

What Are the Symptoms of Code P0134?

  • Check Engine Light
  • Higher emissions
  • Excessive smoke from the exhaust
  • Poorly running engine
  • Lower fuel economy

*No noticeable adverse conditions in some cases

What Is the Cause of Code P0134?

  • Faulty O2 sensor
  • Faulty heater circuit
  • A frayed or broken wiring 
  • Poor connection at the O2 sensor connector
  • Engine Vacuum Leak
  • Exhaust Leak
  • Faulty ECM

How Serious is Code P0134? – Moderate

While this trouble code will likely not prevent your vehicle from running, over time it could cause damage to the catalytic converter, which could affect your vehicle’s ability to run cleanly and efficiently. The most common impact of this trouble code is a decrease in your vehicle’s fuel economy.

Code P0134 Common Diagnosis Mistakes   

Prematurely replacing the oxygen sensor when the issue lies within the wiring or connectors which could have been diagnosed by a visual inspection.

Tools Needed to Diagnose Code P0134:

How to Diagnose Code P0134:

Difficulty of Diagnosis and Repair – 2 out of 5

  1. Check to see if there are any other codes along with P0134, and clear your Check Engine Light with FIXD
  2. Visually inspect wiring at the O2 sensor for fray or breakage. Also, check the connector for good connection and no corrosion.
  3. Replace vacuum lines or intake air tube if there are signs of cracks or disconnections.
  4. Check for any exhaust leaks between the engine and the O2 sensor. Repair as needed.
  5. Check for varying voltage of between .1-.95V with the engine running at operating temperature. If this reading isn’t within spec, consider replacing the O2 sensor 1 on bank 1
  6. Check the wire from ECM to the O2 sensor for continuity.
  7. If continuity exists, and you have already replaced the O2 sensor, there is a possible internal fault of the ECM. Consider replacing the ECM, or taking it to a shop for further diagnosis.

Estimated Cost of Repair

For error code P0134, 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. 

  • Air fuel sensor or oxygen sensor $200-$300
  • Wiring repair/replacement $100-$1000
  • Vacuum/Intake leak $100-$200
  • Exhaust repair $100-$200 (if welded to repair)
  • ECM $1000-$1200

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  1. Yes it was helpful thanks

    1. Yes it was very forward and helpful..

      1. I changed the sensor a number of times and the seem to continue to read o2 sensor bank one every year before I need a smog what could it be replacing them every year?

    2. I have no 02 sesors in my harley exhaust so i installed new 02 sensor elimanator plugs and still the check engine light comes on

      1. Vacuum leak?

  2. What would be more helpful would be the multimeter readings we should see at the connector terminals, and the mm setting it should be on.

  3. I have a 05 civic hybrid and changed the o2 air flow sensor and it still comes up that the heater in not working

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