P1850: Brake Band Apply Solenoid Circuit OBD-II Trouble Code

The transmission brake band is used to stop a spinning drum inside the transmission to allow for a gear change. Having a P1850 diagnostic trouble code means there is an issue with the brake band apply solenoid, which is used to direct the flow of pressurized hydraulic fluid/ATF that activates the transmission band.

Need a replacement transmission? Get an estimate for replacement transmissions and local installation. Look up your transmission model by vehicle make and model.

What Transmission Do I Have?

How Serious is the Code?

A P1850 OBDII diagnostic trouble code is a very serious DTC, because it means the ECU/TCM is not in full control of the brake band. This is one of the most important transmission parts, as it facilitates a gear change. Problems with this can result in serious drivability issues.

Symptoms

Symptoms of a P1850 include:

  • Slipping
  • Delayed gear changes
  • Erratic transmission behavior
  • Burning smell coming from the transmission
  • Transmission overheating
  • Check engine light

Causes

  • Dirty transmission fluid
  • Blocked hydraulic passages
  • Valve body issues
  • Damaged/corroded wiring or connectors
  • Failed brake band apply solenoid

How to Diagnose the Code?

With diagnosing a P1850 DTC, it’s important to pay attention to the condition of the transmission fluid, as this can have a huge effect on the operation of the brake band solenoid. If the transmission fluid is in good condition, then the valve body and brake band solenoid should be investigated as a possible culprit for the problem.

Need a replacement transmission? Get an estimate for replacement transmissions and local installation. Look up your transmission model by vehicle make and model.

What Transmission Do I Have?

What Repairs Will Fix P1850?

  • Change the transmission fluid and filter
  • Replace or repair damage wiring/connectors
  • Replace brake band apply solenoid

Related Codes

P1851 – Brake Band Apply Solenoid Performance
P1852 – Brake Band Apply Solenoid Low Voltage
P1853 – Brake Band Apply Solenoid High Voltage