OBD Guide
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P18B7

Internal Mode Switch 'C' Circuit Shorted

P18B7 is an OBD-II diagnostic trouble code meaning: Internal Mode Switch 'C' Circuit Shorted. Common causes: short circuit in switch circuit, malfunction of the internal mode switch. Estimated repair cost: $17–56.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$17–56 (est.)

Symptoms

  • Incorrect display of the current transmission mode on the instrument panel
  • Gear shifting problems
  • Check Engine light comes on
  • The car may not start in some modes

Causes

  • Short circuit in switch circuit
  • Malfunction of the internal mode switch
  • Wiring harness damage
  • Problems with the transmission control module
  • Corrosion of electrical contacts

How to Fix

  1. Check the integrity of the wiring in the switch circuit
  2. Test switch resistance
  3. Check connections and contacts for corrosion
  4. If necessary, replace the internal mode switch
  5. Reset the error code and check if it returns

Related codes

P18B6P18B8P18B9

FAQ

What does the P18B7 code mean?

P18B7 is an OBD-II diagnostic trouble code that indicates: Internal Mode Switch 'C' Circuit Shorted

What causes a P18B7 error code?

The most common causes of P18B7 include: Short circuit in switch circuit; Malfunction of the internal mode switch; Wiring harness damage; Problems with the transmission control module.

How do I fix a P18B7 diagnostic trouble code?

To fix P18B7: Check the integrity of the wiring in the switch circuit. Test switch resistance. Check connections and contacts for corrosion. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P18B7?

Limited driving only, diagnose soon

How much does it cost to fix P18B7?

The estimated repair cost for P18B7 is $17–56. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat