P18B8
Internal Mode Switch 'P' Circuit Shorted
P18B8 is an OBD-II diagnostic trouble code meaning: Internal Mode Switch 'P' Circuit Shorted. Common causes: short circuit in mode switch circuit, wiring harness damage. Estimated repair cost: $17–89.
Symptoms
- Incorrect display of gear selector position on the dashboard
- Trouble starting the engine (especially in P or N position)
- The gearbox does not respond to mode switching
- Check Engine Light Is On
- Activating emergency transmission mode
Causes
- Short circuit in mode switch circuit
- Wiring harness damage
- Malfunction of the internal mode switch
- Transmission Control Module (TCM) Problems
- Corrosion of contacts or connectors
How to Fix
- Check the integrity of the wiring and connectors in the switch circuit
- Check the resistance of the mode switch
- Inspect the condition of the contacts on the connectors
- Check the operation of the transmission control module
- If necessary, replace the mode switch
Related codes
FAQ
What does the P18B8 code mean?
P18B8 is an OBD-II diagnostic trouble code that indicates: Internal Mode Switch 'P' Circuit Shorted
What causes a P18B8 error code?
The most common causes of P18B8 include: Short circuit in mode switch circuit; Wiring harness damage; Malfunction of the internal mode switch; Transmission Control Module (TCM) Problems.
How do I fix a P18B8 diagnostic trouble code?
To fix P18B8: Check the integrity of the wiring and connectors in the switch circuit. Check the resistance of the mode switch. Inspect the condition of the contacts on the connectors. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P18B8?
Do not drive — repair immediately
How much does it cost to fix P18B8?
The estimated repair cost for P18B8 is $17–89. Actual cost depends on your vehicle, location, and labor rates.
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