P014A: O2 Sensor Delayed Response - Rich to Lean Bank 2 Sensor 2
What to do
Ask whether the same fault is stored for the other bank. If both sides are affected, the cause is something shared — fuel quality or a fuelling problem — rather than two failed sensors, and that changes the repair completely.
Ask for the bank to be confirmed against the manufacturer's diagram before a sensor is replaced. Bank 2 is not always the side you would expect, and fitting a sensor to the wrong bank is a common and avoidable expense.
Ask for the exhaust to be checked for leaks on that side, which is a frequent cause and often audible as a tick when the engine is cold.
The car will usually drive normally, so this is an MOT concern rather than an urgent one.
What this code means
The downstream oxygen sensor on bank 2 is not beginning its rich-to-lean transition when it should.
This is the bank 2 counterpart of P013E, and the fact that there are two banks is itself the most useful diagnostic tool available here. A V engine gives you a built-in control. Bank 1 and bank 2 do the same job with the same hardware in the same conditions, so comparing the two sensors' behaviour side by side answers questions that neither answers alone.
- One bank delayed, the other normal — the fault is specific to this bank: its sensor, its exhaust section, or a leak on that side.
- Both banks delayed together — look for something shared. Fuel quality, a fuelling strategy problem, or a purge valve stuck open affect both banks equally, and replacing two sensors will not fix any of them.
That second case is the expensive mistake this code invites, because two lazy-looking downstream sensors are a very plausible-sounding diagnosis and two sensors are a real bill.
Bank identification is the other trap. Bank 1 is the bank containing cylinder 1, which is not always the side nearest the front of the car and differs between manufacturers. Confirm it against the manufacturer's own diagram — replacing the sensor on the wrong bank is a common and entirely avoidable outcome.
The causes are its sibling's: an exhaust leak, a sensor out of the flow, a fouled element, or honest age.
Likely causes
Start here
- Exhaust leak upstream of the sensor · moderate
- Aging or slow oxygen sensor · moderate
Less common
- Oxygen sensor not correctly seated · moderate
- Metal debris on the sensor tip · moderate
- Engine burning oil into the exhaust · specialist
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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