P015D
O2 Sensor Delayed Response - Lean to Rich Bank 2 Sensor 1
Fuel & air metering (O2 sensor)
Generic OBD-II
Medium
What it means
P015D means the upstream oxygen sensor on bank 2 (sensor 1) takes too long to react when the mixture swings from lean to rich. This front sensor guides the computer's fuel control, so a delayed signal can slightly upset fueling and economy. It's most often an aging sensor, but wiring faults, exhaust or intake leaks, and fuel-delivery problems can trigger the same code.
Medium
Can I keep driving? Usually safe to drive — you may notice slightly worse economy or a mild surge, but it's mainly a fuel-mixture and emissions concern.
Common symptoms
What you'll notice
- Check-engine light on
- Rough idle or mild surging
- Increased fuel consumption
- Failed emissions test
Common causes
Most likely first
- Aged or contaminated upstream oxygen sensor (bank 2, sensor 1)Likely
- Sensor wiring open, shorted, or corrodedCommon
- Poor electrical connection at the sensorCommon
- Intake air or exhaust leaks skewing the readingLess often
- Fuel-delivery issues (pressure or injectors) upsetting the mixtureLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and check the fuel-trim values for bank 2.
- Inspect the sensor wiring and connector for damage or corrosion.
- Check for intake and exhaust leaks near the sensor.
- Verify fuel pressure and injector operation if the trims are skewed.
- Replace the upstream oxygen sensor if it responds slowly with everything else good.
FAQ
Quick answers
Is it safe to drive with P015D?+
Generally yes — the engine still runs, but the slow sensor can slightly upset the mixture and hurt economy. Fix it before an emissions test or if idle gets rough.
Can I just clear P015D?+
It will return after a few drive cycles unless the sluggish sensor, its wiring, or an underlying mixture problem is corrected.
Related codes
Often seen with P015D
Read & clear P015D yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX