OBD Guide

P305B

DC/DC Converter Ignition On/Start Switch Circuit High Voltage

P305B is an OBD-II diagnostic trouble code meaning: DC/DC Converter Ignition On/Start Switch Circuit High Voltage. Common causes: dc/dc converter malfunction, problems with wiring or harness. Estimated repair cost: $56–167.

Severity
🔴 High
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$56–167 (est.)

Symptoms

  • The car won't start
  • Dashboard flashing or turning off
  • Problems with car electronic systems
  • Warning messages on display
  • Reduced hybrid system performance (if applicable)

Causes

  • DC/DC converter malfunction
  • Problems with wiring or harness
  • Short circuit in the circuit
  • Ignition switch malfunction
  • Problems with the control unit

How to Fix

  1. Check the voltage in the ignition switch circuit
  2. Inspect the wiring harness for damage
  3. Check the operation of the DC/DC converter
  4. Test the ignition switch
  5. If necessary, replace faulty components

Related codes

FAQ

What does the P305B code mean?

P305B is an OBD-II diagnostic trouble code that indicates: DC/DC Converter Ignition On/Start Switch Circuit High Voltage

What causes a P305B error code?

The most common causes of P305B include: DC/DC converter malfunction; Problems with wiring or harness; Short circuit in the circuit; Ignition switch malfunction.

How do I fix a P305B diagnostic trouble code?

To fix P305B: Check the voltage in the ignition switch circuit. Inspect the wiring harness for damage. Check the operation of the DC/DC converter. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P305B?

Do not drive — repair immediately

How much does it cost to fix P305B?

The estimated repair cost for P305B is $56–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat