Code result
P28F9
Exhaust Pressure Too Low Bank 1
High severity
What it means
The exhaust pressure measured on bank 1 falls below the calibrated minimum. Common causes are leaks upstream of the sensor, missing DPF substrate, or sensor calibration drift.
Is it safe to drive?
No — stop driving
This code can put the vehicle into limp or reduced-power mode. Avoid extended driving and have the vehicle diagnosed promptly.
Most likely causes
Exhaust leak upstream of sensor
highOne of the most commonly reported causes for this code — check this first.
Sensor zero point drifted
mediumA plausible cause — test and verify before replacing parts.
Related help
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