OBD Guide

P1838

Internal Mode Switch 'A' Circuit High Voltage

P1838 is an OBD-II diagnostic trouble code meaning: Internal Mode Switch 'A' Circuit High Voltage. Common causes: short circuit to power in switch circuit, broken or damaged wiring. Estimated repair cost: $17–67.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$17–67 (est.)

Symptoms

  • Incorrect display of the current transmission mode on the dashboard
  • Gear shifting problems
  • Check Engine Light Illuminates
  • The transmission may go into emergency mode
  • The car may not start in some selector positions

Causes

  • Short circuit to power in switch circuit
  • Broken or damaged wiring
  • Switch contact corrosion
  • Malfunction of the internal mode switch
  • Transmission control module (TCM) problems

How to Fix

  1. Check the integrity of the wiring and connectors in the switch circuit
  2. Measure resistance and voltage at the mode switch
  3. Check for short circuit to power
  4. If necessary, replace the mode switch
  5. Scan the transmission control module for additional errors

Related codes

Error P1838 by Vehicle Brand

FAQ

What does the P1838 code mean?

P1838 is an OBD-II diagnostic trouble code that indicates: Internal Mode Switch 'A' Circuit High Voltage

What causes a P1838 error code?

The most common causes of P1838 include: Short circuit to power in switch circuit; Broken or damaged wiring; Switch contact corrosion; Malfunction of the internal mode switch.

How do I fix a P1838 diagnostic trouble code?

To fix P1838: Check the integrity of the wiring and connectors in the switch circuit. Measure resistance and voltage at the mode switch. Check for short circuit to power. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P1838?

Limited driving only, diagnose soon

How much does it cost to fix P1838?

The estimated repair cost for P1838 is $17–67. Actual cost depends on your vehicle, location, and labor rates.

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