What it means
The measured current of the second auxiliary transmission fluid pump motor is above the upper threshold. Pump binding or motor shorted.
At a glance
- Usually lights the check-engine light
How it works
An auxiliary transmission fluid pump moves fluid when the transmission needs extra circulation or pressure, and Pump B is the second pump identified by the vehicle’s control system. The controller monitors Pump B motor current while it runs. This code sets when current rises above the allowed threshold, which can happen if the impeller binds or the motor winding is internally shorted.
Common causes
Most likely first.
- Impeller binding from sediment or wear
- Internal short in motor winding
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Use a scan tool to save freeze-frame data and check when Pump B was commanded on, along with transmission temperature and any related pressure or shift codes.
- With the vehicle safely parked, inspect Pump B’s connector and harness for damage, corrosion, loose pins, or fluid intrusion.
- Check the scan-tool data for Pump B command and current, if available, and see whether the high-current fault returns when the pump is commanded.
- With the circuit powered down as specified by the manufacturer, inspect the pump and its wiring for a short or damaged insulation before testing continuity.
- If the wiring checks out, test the Pump B motor and impeller for an internal short or binding, using the manufacturer’s procedure.
Common fixes
- Repair damaged or corroded Pump B wiring or connector terminals.
- Clean and secure a loose Pump B electrical connection.
- Replace the Pump B motor if its winding is shorted.
- Replace the auxiliary pump assembly if its impeller is binding or worn.
Can I keep driving?
Avoid towing, hard acceleration, and long trips if shifts are harsh, delayed, slipping, or shuddering; inadequate fluid circulation can worsen transmission damage. If the transmission enters limp mode or loses drive, stop in a safe place and arrange recovery.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.