OBD Guide

P0B09

Electric/Auxiliary Transmission Fluid Pump A Motor Supply Voltage Circuit/Open

P0B09 is an OBD-II diagnostic trouble code meaning: Electric/Auxiliary Transmission Fluid Pump A Motor Supply Voltage Circuit/Open. Common causes: broken wires in the pump power circuit, pump motor malfunction. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Check Engine light comes on
  • Transmission transition to emergency mode
  • Gear shifting problems
  • Unusual noises from the transmission area
  • Reduced transmission efficiency

Causes

  • Broken wires in the pump power circuit
  • Pump motor malfunction
  • Relay or fuse problems
  • Oxidation or damage to contacts
  • Transmission control unit malfunction

How to Fix

  1. Check the pump circuit fuses and relays
  2. Inspect the wiring harness for damage
  3. Check the voltage at the pump terminals
  4. Test the operation of the pump motor
  5. If necessary, replace the pump or damaged wires

Related codes

Error P0B09 by Vehicle Brand

FAQ

What does the P0B09 code mean?

P0B09 is an OBD-II diagnostic trouble code that indicates: Electric/Auxiliary Transmission Fluid Pump A Motor Supply Voltage Circuit/Open

What causes a P0B09 error code?

The most common causes of P0B09 include: Broken wires in the pump power circuit; Pump motor malfunction; Relay or fuse problems; Oxidation or damage to contacts.

How do I fix a P0B09 diagnostic trouble code?

To fix P0B09: Check the pump circuit fuses and relays. Inspect the wiring harness for damage. Check the voltage at the pump terminals. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P0B09?

Limited driving only, diagnose soon

How much does it cost to fix P0B09?

The estimated repair cost for P0B09 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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