P2195 – Heated Oxygen Sensor (H02S) Bank 1 Sensor 1 – Signal Stuck Lean

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By Stephen Darby (Contact Me)
Last Updated 2017-03-31
ASE Master Tech
CodeFault LocationProbable Cause
P2195 Heated oxygen sensor (H02S) 1, bank 1 - signal stuck lean
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H02S, fuel pressure, injectors, intake leak

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Table of Contents

  1. What Does Code P2195 Mean?
  2. What are the common causes of code P2195?
  3. What are the symptoms of code P2195?
  4. How do you troubleshoot code P2195?
  5. Codes Related to P2195
  6. Get Help with P2195

What Does Code P2195 Mean?

So, your OBD-II equipped vehicle has a stored code P2195? It simply means that the powertrain control module (PCM) has detected a signal from the upstream (or pre catalytic converter) oxygen (O2) sensor or circuit that is apparently stuck or improbable. Bank 1 denotes the bank of the engine that contains the number one cylinder and Sensor 1 indicates that the malfunction is related to the upstream sensor.

Oxygen sensors are composed using a zirconium dioxide sensing element that is protected by a vented steel housing. Most manufacturers use platinum electrodes to connect the sensing element to wire leads in the O2 sensor wiring harness. The controller area network (CAN) is used to connect the O2 sensor wiring harness to the PCM. The O2 sensor supplies the PCM with data pertaining to the number of oxygen particles in the engine exhaust as compared to the percentage of oxygen content in the surrounding ambient air.




In automotive applications, exhaust gases are pushed into the exhaust pipe and through the catalytic converter. They leave the catalytic converter and pass over the downstream O2 sensor. Ambient air is drawn through the wire lead cavities and into a small chamber in the middle of the sensor, as exhaust flows through vent holes (in the steel housing) and across the sensing element. When the ambient air in the chamber is heated by the exhaust, the oxygen ions produce (energy) voltage. Differences between the number of oxygen molecules in ambient air (drawn into the O2 sensor) and the concentration of oxygen ions in engine exhaust cause the voltage levels to change. These variations cause the oxygen ions inside the O2 sensor to bounce between the platinum layers rapidly and repetitiously. Voltage alterations occur as the rushing oxygen ions bounce between the platinum layers. These variations in voltage are identified by the PCM as changes in exhaust oxygen concentration. This data suggests that the engine is either running lean (too little fuel) or rich (too much fuel). The voltage signal from the O2 sensor is low (as low as .01-volts) when more oxygen is present in the exhaust (lean condition) and high (as much as .900-volts) when less oxygen is present in the exhaust (rich condition). O2 sensor data is used by the PCM to calculate fuel delivery and ignition timing, as well as other engine drivability functions.

If the upstream O2 sensor circuit fails to cycle as expected or inputs an improbable signal to the PCM, a code P2195 will be stored and a malfunction indicator lamp may be illuminated.

What are the common causes of code P2195?

  • Defective O2 sensor/s
  • Burnt, broken, or disconnected wiring and/or connectors
  • Engine exhaust leaks
  • Large engine vacuum leak
  • Defective mass air flow or manifold absolute pressure sensor
  • Faulty exhaust gas recirculation (EGR) valve

What are the symptoms of code P2195?

  • A lack of general engine performance
  • Diminished fuel efficiency
  • Other related diagnostic trouble codes may also be stored
  • Service engine soon lamp illumination

How do you troubleshoot code P2195?

A diagnostic scanner, digital volt ohmmeter (DVOM), and a reliable vehicle information source (such as All Data DIY) are among the tools that I would use to diagnose a code P2195.

Misfire codes, throttle position sensor codes, manifold air pressure code, and mass air flow sensor codes should be diagnosed and rectified prior to attempting a diagnosis for a code P2195. An engine that is not running efficiently will make a successful diagnosis (of P2195) impossible.

My technicians and I, typically begin with a visual inspection of system wiring harnesses and connectors. I tend to focus on harnesses that are routed near hot exhaust pipes and manifolds, as well as those that are located near sharp edges like the ones found on exhaust shields.

We usually continue by connecting the scanner to the vehicle diagnostic port and retrieving all stored trouble codes and freeze frame data. I make it a practice to write this information down as it may be helpful if the P2195 seems to be intermittent. Clear the codes and see if a code P2195 is reset.





Should the P2195 be reset, start the engine and let it idle (with the transmission in neutral or park). This should be done after allowing the engine to reach normal operating temperature. Narrow the data stream display to include only pertinent data and observe O2 sensor input. By narrowing the data stream, you can get a faster data response.  If the engine is running efficiently, upstream O2 sensor data should fluctuate regularly between .001 and .900-volts (with the engine at idle).

To monitor live data from the upstream O2 sensor, connect the DVOM test leads to the sensor ground and signal wires with the engine idling. The DVOM may also be used to check voltage and ground signals and resistance of the O2 sensor in question. Disconnect related controllers prior to testing system circuit resistance with the DVOM. Use caution when working near hot exhaust components.

  • P0100 Mass or Volume Air Flow Circuit Malfunction
  • P0101 Mass or Volume Air Flow Circuit Range/Performance Problem
  • P0102 Mass or Volume Air Flow Circuit Low Input
  • P0103 Mass or Volume Air Flow Circuit High Input
  • P0104 Mass or Volume Air Flow Circuit Intermittent
  • P0105 Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction
  • P0106 Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem
  • P0107 Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
  • P0108 Manifold Absolute Pressure/Barometric Pressure Circuit High Input
  • P0109 Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent
    P0130 02 Sensor Circuit Malfunction (Bank I Sensor 1)
  • P0131 02 Sensor Circuit Low Voltage (Bank I Sensor I)
  • P0132 02 Sensor Circuit High Voltage (Bank I Sensor 1)
  • P0133 02 Sensor Circuit Slow Response (Bank 1 Sensor 1)
  • P0134 02 Sensor Circuit No Activity Detected (Bank I Sensor 1)
  • P0300 Random/Multiple Cylinder Misfire Detected
  • P0301 through P0312 Cylinders (1 – 12) Misfire Detected
  • P2187 System Too Lean at Idle Bank 1
  • P2188 System Too Rich at Idle Bank 1
  • P2195 O2 Sensor Signal Stuck Lean Bank1 Sensor 1
  • P2196 O2 Sensor Signal Stuck Rich Bank1 Sensor 1

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