P0844

Transmission Fluid Pressure Sensor/Switch "A" Circuit Intermittent

Severity: High
Driving: Drive only to a garage

The signal from transmission fluid pressure sensor or switch "A" is dropping out intermittently. The transmission may drive normally for long periods and then shift badly or enter limp mode, recovering after a restart. Intermittent faults here are usually connections rather than the sensor.

Possible causes

CommonLoose or corroded pin at the transmission case connector
CommonFluid wicking into the connector
CommonInternal transmission harness beginning to fail
PossibleSensor dropping out when hot
PossibleChafed wiring making intermittent contact
PossibleGenuinely fluctuating pressure from a sticking valve

What you might notice

Occasional limp mode clearing after a restart
Shift quality varying between journeys
Symptoms appearing only when hot
Check engine light coming and going

What to check, in order

Note whether it only happens hot, and record the freeze frame fluid temperature if the tool supports it.
Pull the case connector and inspect for fluid and corrosion.
Wiggle-test the external harness with the live data screen showing the pressure reading.
Check the fluid level and condition.
Do not commit to internal repairs until the external wiring and connector are cleared.

Read this code from your own car

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Where this code sits

B · Body C · Chassis P · Powertrain U · Network and communication