P014B: O2 Sensor Delayed Response - Lean to Rich Bank 2 Sensor 2
What to do
Ask how many of these delayed-response faults are stored across both banks. If several are, the sensors are probably fine and something shared is at fault — four delayed sensors is a fuelling problem, not four failed parts, and that is worth establishing before any are replaced.
Ask whether the evaporative purge valve has been checked. One stuck open lets fuel vapour into the engine at unexpected moments and produces exactly this pattern across all the sensors.
Mention any smell of fuel, which would support that.
The car will usually drive normally, so plan the repair around your MOT rather than treating it as urgent.
What this code means
The downstream oxygen sensor on bank 2 is not beginning its lean-to-rich transition when it should.
This is the bank 2 counterpart of P013F, and it completes the set of four downstream delayed-response codes. With all four available, the pattern across them is genuinely diagnostic and worth reading before anything is removed.
- One direction on one bank — that sensor, or that bank's exhaust.
- Both directions on one bank — a leak or a transport problem on that side.
- One direction on both banks — something shared and directional, such as a purge valve or the fuel itself.
- All four — a fuelling or strategy fault rather than the sensors.
The bottom row is the one that saves money. Four delayed downstream sensors are not four failed sensors — they are an engine whose mixture is not doing what the module believes it is doing, and the sensors are reporting that faithfully.
An evaporative purge valve stuck open is a classic producer of that pattern. It admits fuel vapour to the intake at moments the module has not accounted for, so the real mixture transitions late relative to the commanded one — on every sensor at once.
Where the fault is genuinely confined to this sensor, the ordinary causes apply: an exhaust leak on this bank, a sensor not seated to depth, a cracked body admitting reference air, or honest age.
Likely causes
Start here
- Exhaust leak upstream of the sensor · moderate
- Aging or slow oxygen sensor · moderate
Less common
- Faulty EVAP purge valve · easy
- Cracked or damaged oxygen sensor body · moderate
- Oxygen sensor not correctly seated · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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