P2240: O2 Sensor Positive Current Control Circuit/Open Bank 2 Sensor 1
What to do
Expect worse economy and reduced power. If the same fault is stored for bank 1, mention it before parts are agreed — two of these sensors failing at once is unlikely, and something they share is both more probable and much cheaper.
What this code means
An open positive current control circuit on the second bank's upstream sensor. The wideband mechanism, and the warning that a narrowband voltage test will wrongly condemn a good sensor, are both at P2237.
The bank comparison is worth making here as it is throughout this range. One bank alone points at that side's harness or sensor, which is a genuinely narrowed search. Both banks together points at what they share — the module's output stage, or a common connector or ground — and two wideband sensors are an expensive pair to replace for a fault belonging to neither.
Likely causes
Start here
- Open circuit in sensor wiring · moderate
- Corroded or loose connector · easy
- Faulty oxygen sensor · moderate
Less common
- Damaged wiring harness · moderate
Rare
- Faulty engine control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
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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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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