P0129: Barometric Pressure Too Low
What to do
Usually driveable with slightly compromised fuelling. Worth diagnosing, as the same sensor often affects load calculation more broadly.
What this code means
The barometric pressure reading has fallen below the plausible range. Genuine atmospheric pressure only gets so low, even at considerable altitude, so a reading beneath that floor usually means a sensor problem rather than the weather. Where the barometric value is derived from the manifold pressure sensor at key-on rather than from a dedicated sensor, a MAP sensor fault will present here instead.
Likely causes
Start here
- Faulty barometric pressure sensor · moderate
- Faulty manifold absolute pressure sensor · easy
Less common
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
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
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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