P0129 — Barometric Pressure Too Low
Seen on: Heavy Truck
Barometric Pressure Too Low. Common causes: BARO sensor reading below minimum.
Your code rides along, so nearby mechanics see the fault before they quote you.
How serious is it?
Informational. Usually OK to continue — monitor closely.
Most likely causes
- BARO sensor reading below minimum
- Sensor failure
- ECM altitude error
First moves (roadside)
- Compare BARO reading to expected pressure at altitude
- replace sensor if off by >0.5 psi
FAQ
Barometric Pressure Too Low. Common causes: BARO sensor reading below minimum.
Informational — Usually OK to continue — monitor closely.
The most common cause is: BARO sensor reading below minimum. Other possibilities include Sensor failure; ECM altitude error.
Usually OK to continue — monitor closely. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.