OBD Guide

P18B6

Internal Mode Switch 'B' Circuit Shorted

P18B6 is an OBD-II diagnostic trouble code meaning: Internal Mode Switch 'B' Circuit Shorted. Common causes: short circuit in switch wiring harness, 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
  • Gear shifting problems
  • Transmission transition to emergency mode
  • Check Engine light comes on
  • The car may not start in some selector positions

Causes

  • Short circuit in switch wiring harness
  • Malfunction of the internal mode switch
  • Damage to connectors or corrosion of contacts
  • Problems with the transmission control unit
  • Mechanical damage to the wiring in the gear selector area

How to Fix

  1. Conduct a visual inspection of the switch wiring and connectors
  2. Check the resistance and continuity of the switch circuit
  3. Test the operation of the internal mode switch
  4. Check for software updates for the control unit
  5. If necessary, replace the switch or repair the wiring

Related codes

FAQ

What does the P18B6 code mean?

P18B6 is an OBD-II diagnostic trouble code that indicates: Internal Mode Switch 'B' Circuit Shorted

What causes a P18B6 error code?

The most common causes of P18B6 include: Short circuit in switch wiring harness; Malfunction of the internal mode switch; Damage to connectors or corrosion of contacts; Problems with the transmission control unit.

How do I fix a P18B6 diagnostic trouble code?

To fix P18B6: Conduct a visual inspection of the switch wiring and connectors. Check the resistance and continuity of the switch circuit. Test the operation of the internal mode switch. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P18B6?

Limited driving only, diagnose soon

How much does it cost to fix P18B6?

The estimated repair cost for P18B6 is $17–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat