P0159

O2 Sensor Circuit Slow Response Bank 2 Sensor 2

Q: Is it safe to drive with P0159?

Yes. This rear sensor mainly grades the catalytic converter, so driveability is essentially unchanged. Fix it for emissions and to keep the light off.

Q: Can I just clear P0159?

It will return once the ECM re-tests the sensor unless the lazy sensor or an exhaust leak behind it is repaired.

Oxygen sensor Generic OBD-II Medium

What it means

P0159 means the downstream oxygen sensor on bank 2 (sensor 2) is switching too slowly between rich and lean. As a rear sensor it mainly grades catalytic-converter performance rather than controlling fuel, so this rarely changes how the car drives. It's usually just an aging sensor, and it keeps the check-engine light on and can fail an emissions test.

Medium

Can I keep driving? Safe to drive — as a downstream sensor this barely affects driveability, but the light stays on and it can fail emissions.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Fails emissions or won't complete readiness monitors
Slightly worse fuel economy

Common causes

Most likely first

Aged or contaminated downstream O2 sensor (most common)Likely
Exhaust leak near the sensor skewing its readingsCommon
Damaged wiring or connector at the sensorCommon
Sensor contamination from burning oil or coolantLess often
Rarely, a failing ECMLess often

How to diagnose & fix

Work through it in order

View the bank 2, sensor 2 switching speed in live data to confirm it's lazy.
Inspect the exhaust for leaks upstream of the sensor.
Check the sensor connector and wiring for damage or corrosion.
Replace the downstream O2 sensor if it's simply aged out.
Clear the code and re-test to confirm response speed recovers.

FAQ

Quick answers

Is it safe to drive with P0159?+

Yes. This rear sensor mainly grades the catalytic converter, so driveability is essentially unchanged. Fix it for emissions and to keep the light off.

Can I just clear P0159?+

It will return once the ECM re-tests the sensor unless the lazy sensor or an exhaust leak behind it is repaired.

Read & clear P0159 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX