P27A8: Pressure Control Solenoid B Data Incompatible

What it means

The calibration data programmed for pressure control solenoid B does not match the format expected by the transmission controller.

At a glance

• Usually lights the check-engine light

How it works

Pressure control solenoid B adjusts transmission hydraulic pressure when directed by the TCM. This code sets when the calibration data for solenoid B is incompatible with the format or version expected by the controller, preventing it from applying the intended solenoid settings.

Common causes

Most likely first.

1. Replacement solenoid incompatible with software version
2. Calibration code format does not match controller version

Symptoms

• Check engine or transmission warning light may be on
• Harsh, delayed, or erratic shifting
• Transmission may enter a limited operating mode

How to diagnose it

1. Save freeze-frame data and check for related transmission codes, noting whether the issue began after work on solenoid B or the transmission.
2. Verify that the installed pressure control solenoid B is compatible with the transmission and current TCM software version.
3. Read solenoid B's calibration data and compare its format with the requirements for that controller.
4. Review the programming or installation record to confirm solenoid B's calibration was entered correctly.
5. If the solenoid and data match, check vehicle-specific service information for a required TCM software update or calibration.

Common fixes

• Program the correct calibration data for pressure control solenoid B.
• Replace an incompatible solenoid B with a compatible unit.
• Correct the calibration format or entry for solenoid B.
• Update or reprogram the TCM if required by vehicle-specific service information.

Can I keep driving?

Limit driving if shifts are harsh, delayed, or erratic, or if the transmission enters a limited operating mode, because incorrect pressure control can increase wear. Stop driving if the vehicle cannot shift predictably.