OBD Guide

P18B5

Internal Mode Switch 'A' Circuit Shorted

P18B5 is an OBD-II diagnostic trouble code meaning: Internal Mode Switch 'A' Circuit Shorted. Common causes: short circuit in mode switch circuit, malfunction of the internal mode switch. Estimated repair cost: $17–89.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$17–89 (est.)

Symptoms

  • Incorrect display of gear selector position on the instrument panel
  • The car does not start in some selector positions
  • The gearbox goes into emergency mode
  • Gear shifting problems
  • Check Engine light comes on

Causes

  • Short circuit in mode switch circuit
  • Malfunction of the internal mode switch
  • Wiring harness damage
  • Problems with the transmission control unit
  • Oxidation of contacts

How to Fix

  1. Check the integrity of the wiring and connections in the switch circuit
  2. Test the resistance of the mode switch
  3. Check for short circuit in the circuit
  4. If necessary, replace the mode switch
  5. Flash or replace the transmission control unit if necessary

Related codes

FAQ

What does the P18B5 code mean?

P18B5 is an OBD-II diagnostic trouble code that indicates: Internal Mode Switch 'A' Circuit Shorted

What causes a P18B5 error code?

The most common causes of P18B5 include: Short circuit in mode switch circuit; Malfunction of the internal mode switch; Wiring harness damage; Problems with the transmission control unit.

How do I fix a P18B5 diagnostic trouble code?

To fix P18B5: Check the integrity of the wiring and connections in the switch circuit. Test the resistance of the mode switch. Check for short circuit in the circuit. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P18B5?

Limited driving only, diagnose soon

How much does it cost to fix P18B5?

The estimated repair cost for P18B5 is $17–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat