P0159: O2 Sensor Circuit Slow Response Bank 2 Sensor 2
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Yes - no immediate effect on how the car drives.
Symptoms
- Check engine light only
- Emissions readiness monitors not completing
- No performance change
Likely causes, most common first
- Bank 2 downstream sensor aged
- Sensor coated with deposits
- Small exhaust leak behind the converter
- Oil consumption poisoning the sensor
Read P0159 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
P0159 reports slow response from the bank 2 downstream sensor. Slow response is the normal end of an oxygen sensor's life; most are designed for roughly a hundred thousand miles, and few give trouble before that.
If a downstream sensor is being replaced for slow response, note the mileage. A sensor that ages out at 60,000 miles is telling you something about what is passing through the exhaust - usually oil consumption - and that underlying problem will shorten the life of the catalytic converter too.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Cars that report P0159 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0159?
Yes - no immediate effect on how the car drives.
How much does it cost to fix P0159?
Typical US repair costs range from $150 for the simplest fix (downstream oxygen sensor) to $600 in the worst case. The right number depends on which cause your car has - see the causes list.
Related codes
The codes closest to P0159. They often appear together, and telling them apart is usually what narrows the diagnosis.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.