Fault code P015B – O2 sensor delayed response – lean to rich (Bank 1, Sensor 1)

Fault code P015B is called “O2 Sensor Delayed Response – Lean to Rich (Bank 1, Sensor 1)” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P015B

This Diagnostic Trouble Code (DTC) is a generic code. Error P015B is considered a generic code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.

Fault code P015B – O2 sensor delayed response – lean to rich (Bank 1, Sensor 1)

When OBD-II code P015B is saved, the transmission control module (PCM) detects the response delay from the 1st oxygen sensor O₂. In this case, the response delay is from lean to rich mixture condition. Bank 1 identifies the engine group that contains cylinder 1.

The oxygen sensors are designed with a zirconium dioxide sensing element. Which is protected by a specially designed vented steel housing. An electrical signal is sent to the PCM according to the percentage of oxygen particles in the engine exhaust gases. It is compared with the oxygen content of the ambient air.

Deviations between the concentration of oxygen molecules in the ambient air and the concentration of oxygen ions in the exhaust gases cause That the heated oxygen ions inside the O2 sensor move very quickly between the platinum layers.

These voltage changes are identified by the PCM as changes in the oxygen concentration in the exhaust gas. Which indicates that the engine is running on a lean or rich mixture.

If the oxygen sensor O₂ fails to operate quickly or regularly as expected within a specified period of time and under predetermined circumstances. Then the trouble code P015B will be stored, and the indicator lamp on the instrument panel may illuminate.

Symptoms of vehicle malfunctions

The main signal that an error P015B has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be stored as a fault).
  2. Other related fault codes may also be present.
  3. Reduced engine power.
  4. Increased fuel consumption.

Error P015B is not considered serious, the car will be able to start and continue driving. However, ignoring it for a long time may lead to catalytic converter failure and other consequences.

Factors that can cause this error code

The error code P015B can mean that one or more of the following problems have occurred:

  • The oxygen sensor O₂ may be defective.
  • There may be damage to the oxygen sensor O₂ circuit.
  • High resistance or break in the oxygen sensor signal circuit O₂.
  • Clogged catalytic converter.
  • Engine exhaust leakage.

How to fix or reset OBD-2 code P015B

Some suggested steps for troubleshooting and fix the error code P015B:

  1. Read all stored data and error codes with an OBD-II scan tool.
  2. Clear the trouble codes from the computer memory and test-drive the vehicle to find out if error P015B appears again.
  3. Observe the oxygen sensor data in real time using the scan tool. To find out if the voltage drops below 0.2 volts when the vehicle slows down.
  4. Check the oxygen sensor for contamination due to coolant or engine oil leakage. Replace the oxygen sensor O₂ if necessary.
  5. Inspect the electrical wires related to the oxygen sensor for moisture or mechanical damage. Repair any faults found.

Diagnose and repair of problems

Before dealing with our error P015B, make sure that all other codes are diagnosed and repaired. Prepare some tools such as a diagnostic scanner, digital voltmeter. As well as a source of vehicle information.

Visually inspect the system’s wiring harnesses and connectors. Pay particular attention to the harnesses near the hot exhaust pipes and manifolds. Also, those routed near sharp edges of parts.

Then connect the scan tool to the vehicle’s diagnostic port and read any stored trouble codes. This information can be useful if the error turns out to be floating, so write it down for later. Now clear the codes and see if code P015B is cleared.

Now start the engine, let it reach normal operating temperature and let it idle. If the engine is running efficiently, the O₂ sensor data should fluctuate regularly between 1 and 9 millivolts. If the voltage fluctuation is slower than expected, P015B will be stored.

Connect the test leads of the voltmeter to the sensor ground and signal leads to monitor the data from the O₂ sensor in real time. Check the resistance as well as the voltage and ground signals.

To prevent damage to the control module, disconnect the corresponding controllers before testing the system circuit resistance with a voltmeter.

On which vehicles does this problem occur most frequently

Fault code P015B can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Buick (Regal)
  • Chevrolet (Cruze, Impala, Malibu, Silverado, Tahoe)
  • Chrysler
  • Dodge
  • Ford
  • GMC (Sierra, Truck, Yukon)
  • Honda
  • Nissan (Altima)
  • Opel (Insignia)
  • Subaru
  • Toyota
  • Volkswagen

Fault code P015B can sometimes be found with other errors. The most common are the following: P0005, P013E, P013F, P014A, P014B, P014C, P014D, P015A, P015C, P015D, P0171, P05E8, P2270.


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