P2439: Secondary Air Injection System Air Flow/Pressure Sensor Circuit Intermittent/Erratic Bank 2
What to do
The car drives normally. This is hard to reproduce on demand, because the system only runs for about a minute after a cold start — expect the wiring and connector to be inspected rather than the fault demonstrated live.
What this code means
The bank 2 secondary air flow reading jumps or drops out. As at P2434, the system runs only briefly after a genuinely cold start, so the window in which this could be observed is about a minute a day — inspection of the connector and harness is the realistic approach rather than live observation.
Likely causes
Start here
- Corroded or loose connector · easy
- Intermittent wiring fault · moderate
Less common
- Faulty secondary air flow sensor · moderate
- Water ingress into connector · easy
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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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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