What does it mean?
P1844 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Transmission Fluid Pressure Sensor/Switch E Circuit .
Symptoms
- Check engine lamp on with a transmission fault message
- Shift quality varying between harsh, soft and delayed on the same drive
- Slipping under load with the engine flaring between gears
- Wrong gear selection or a missing gear in the shift pattern
- Limp mode, higher fluid temperature and clearly reduced drivability
Likely causes
- Debris or varnish holding the switch contacts in one state
- Fluid low, oxidised or overdue for replacement, so pressure never builds correctly
- Open or grounded wire in the E circuit between the switch and the module
- Case connector corroded or wicking fluid between pins
- Internal harness rubbed through inside the pan
- Valve body wear or a stuck valve preventing pressure reaching the switch
- Failed pressure switch assembly
How to fix it
- Read all codes; a group of pressure switch codes together usually points at contaminated fluid or a worn valve body
- Check fluid level, colour and smell, and inspect the pan magnet for clutch material and metal
- Inspect the case connector and external harness for fluid, corrosion and chafe
- Test the E circuit for continuity, short to ground and short to voltage with the switch disconnected
- Fit a line pressure gauge and compare actual pressure with the switch states shown on the scan tool
- Drop the pan and inspect the internal harness and the pressure switch assembly
- Replace the switch assembly, service the fluid and filter, and address valve body wear if the gauge shows low pressure