Code result
P0840
Transmission Fluid Pressure Sensor/Switch A Circuit Range/Performance
Moderate severity
What it means
The transmission fluid pressure sensor A reading is implausible compared to commanded line pressure. The TCM detects sensor drift or hydraulic leakage.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Pressure sensor drift
highOne of the most commonly reported causes for this code — check this first.
Internal hydraulic leak
mediumA plausible cause — test and verify before replacing parts.
Sensor element aged beyond calibration window
lowLess common, but worth ruling out after the more likely causes.
Related help
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