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P078EPowertrainMonitor

Shift Timing Solenoid B Intermittent

This code means the PCM/ECM has detected an intermittent signal or connection affecting shift timing solenoid b. When this happens, the transmission may not control clutch apply pressure or gear changes correctly, which can lead to harsh shifting, slipping, delayed engagement, or fail-safe mode.

Monitor closely — watch for other symptoms. Safe to drive short distances for now.

What You Might Notice

  • Check Engine Light illuminated
  • Harsh or delayed shifting
  • Transmission slipping or wrong gear feel
  • Vehicle may enter limp mode
  • Poor acceleration

Most Common Causes

  1. 1

    Faulty solenoid, pressure sensor, or actuator

  2. 2

    Loose connector, rubbed-through wiring, or vibration-related fault

  3. 3

    Low, dirty, or incorrect transmission fluid

  4. 4

    Internal valve body or clutch problem

  5. 5

    Fault in the TCM/PCM or calibration

How to Diagnose It

  1. 1

    Check Faulty solenoid, pressure sensor, or actuatorInspect for signs of failure and test before replacing.

  2. 2

    Check Loose connector, rubbed-through wiring, or vibration-related faultInspect for signs of failure and test before replacing.

  3. 3

    Check Low, dirty, or incorrect transmission fluidInspect for signs of failure and test before replacing.

  4. 4

    Check Internal valve body or clutch problemInspect for signs of failure and test before replacing.

  5. 5

    Check Fault in the TCM/PCM or calibrationInspect for signs of failure and test before replacing.

How to Fix It

  1. 1

    Verify the code with scan data and freeze-frame information

  2. 2

    Check transmission fluid level and condition

  3. 3

    Test the affected sensor, solenoid, or actuator and replace it if faulty

  4. 4

    Repair damaged wiring or poor connections

  5. 5

    Perform relearn procedures or deeper hydraulic/internal diagnosis if needed

Need a deeper diagnosis?

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