P0159 is an OBD-II trouble code indicating that the Engine Control Module (ECM/PCM) has detected a slow response from the oxygen sensor circuit for Bank 2 Sensor 2.
Bank 2 Sensor 2 is normally the downstream oxygen sensor located after the catalytic converter. The exact location depends on the vehicle year, engine configuration, and manufacturer.
P0159 Location by Manufacturer
The code identifies the sensor circuit, but the physical location varies between vehicles. Always verify Bank 2 and Sensor 2 using the specific vehicle's service information.
Chevrolet Silverado
P0159 refers to the downstream oxygen sensor on Bank 2. The exact position depends on the engine and model year.
Toyota
Bank 2 Sensor 2 is normally the downstream oxygen sensor on the Bank 2 exhaust side. Location varies by engine.
Nissan
On applicable V-type engines, P0159 concerns the downstream oxygen sensor for Bank 2. Verify the exact position for the engine.
Jeep Wrangler
P0159 concerns Bank 2 Sensor 2 after the catalytic converter on applicable engines. The exact side varies by engine and year.
Important: Do not assume that Bank 2 is always the driver or passenger side. Confirm the bank and sensor position for the specific vehicle.
Symptoms of P0159
Check Engine Light
The Check Engine Light may illuminate after the ECM detects the slow sensor response.
Poor Fuel Economy
Fuel economy may decrease if the slow response is associated with an underlying mixture problem.
Rough Running
Some vehicles may experience hesitation, rough idle, or reduced engine performance.
Increased Emissions
A slow oxygen sensor can reduce the accuracy of emissions monitoring.
Common Causes of P0159
Slow or Aging O2 Sensor
The sensor may have become contaminated or degraded and no longer responds quickly to exhaust changes.
Contaminated Sensor
Oil, coolant, fuel additives, or other contaminants can reduce sensor performance.
Exhaust Leak
An exhaust leak near the sensor can affect oxygen readings and sensor response.
Wiring or Connector Problem
Damaged wiring, corrosion, or poor connections can interfere with the sensor signal.
Rich or Lean Condition
An underlying fuel mixture problem can affect oxygen sensor behavior and response.
Engine Problem
Misfires, fuel delivery problems, or other engine faults can influence oxygen sensor readings.
Estimated Repair Cost for P0159
O2 Sensor Replacement
$100–$300 approximately, depending on the vehicle and labor.
Wiring Repair
$50–$250 approximately, depending on the damage.
Exhaust Leak Repair
$100–$500+ depending on the leak location and required parts.
Engine or Fuel Repair
$150–$800+ depending on the underlying problem.
These are general estimates only. Actual repair costs vary by vehicle, parts, labor rate, and the cause of P0159.
How to Fix P0159
The correct repair depends on why Bank 2 Sensor 2 is responding slowly. Diagnose the sensor and surrounding systems before replacing parts.
- Inspect the Bank 2 Sensor 2 wiring and connector.
- Check for exhaust leaks near the sensor.
- Check the sensor response using live data.
- Test the sensor according to the manufacturer's procedure.
- Check for rich or lean engine conditions.
- Replace the oxygen sensor if testing confirms that it is slow or defective.
- Clear the code and verify the repair with a road test.
Common Repair Mistakes
Replacing the Sensor Immediately
P0159 does not automatically prove that the oxygen sensor is defective.
Ignoring Exhaust Leaks
An exhaust leak near the sensor can alter oxygen readings and create diagnostic problems.
Ignoring Other Codes
Misfire, fuel mixture, and engine performance codes may identify the real cause.
Replacing the Wrong Sensor
Confirm Bank 2 Sensor 2 before replacing an oxygen sensor.
Assuming the Same Location
Sensor position varies between manufacturers, engines, and model years.
Related OBD-II Codes
P0156
Bank 2 Sensor 2 Circuit Malfunction. A general fault in the oxygen sensor circuit.
P0157
Bank 2 Sensor 2 Low Voltage. The sensor circuit reports a voltage below the expected range.
P0158
Bank 2 Sensor 2 High Voltage. The sensor circuit reports a voltage above the expected range.
P0161
Bank 2 Sensor 2 Heater Circuit. A fault involving the oxygen sensor heater circuit.
P0159 FAQ
What does P0159 mean?
P0159 means the ECM has detected a slow response from the Bank 2 Sensor 2 oxygen sensor.
Is P0159 always caused by a bad oxygen sensor?
No. Exhaust leaks, wiring problems, contamination, and engine mixture problems can also contribute to the code.
Where is Bank 2 Sensor 2?
It is normally the downstream oxygen sensor after the catalytic converter on Bank 2. The exact physical location depends on the vehicle and engine.
Can I drive with P0159?
The vehicle may remain drivable, but the fault should be diagnosed because prolonged emissions or mixture problems can lead to additional issues.
How do I fix P0159?
Inspect the sensor, wiring, connector, and exhaust system, then check live data and engine operating conditions before replacing the sensor.
Can P0159 affect fuel economy?
Yes. Fuel economy can be affected when the slow sensor response is associated with an underlying fuel or engine problem.
Final Result
P0159 indicates a slow response from Bank 2 Sensor 2. The best diagnosis is to verify the sensor response, inspect the wiring and exhaust system, and check for underlying engine or fuel mixture problems before replacing components.