P1820
Internal Mode Switch Circuit 'A' Low
P1820 is an OBD-II diagnostic trouble code meaning: Internal Mode Switch Circuit 'A' Low. Common causes: malfunction of the internal mode switch, open or short circuit in switch circuit. Estimated repair cost: $17–89.
Symptoms
- Incorrect gear shifting
- The gearbox goes into emergency mode
- Check Engine Light Is On
- Difficulty starting the engine in some selector positions
- Inability to switch between gearbox operating modes
Causes
- Malfunction of the internal mode switch
- Open or short circuit in switch circuit
- Poor contact in circuit connectors
- Problems with power or circuit ground
- Transmission control module (TCM) malfunction
How to Fix
- Check the integrity of the mode switch circuit
- Check connections and contacts in connectors
- Check voltage and ground in the circuit
- Test or replace internal mode switch
- If necessary, reflash or replace the transmission control unit
Related codes
Error P1820 by Vehicle Brand
FAQ
What does the P1820 code mean?
P1820 is an OBD-II diagnostic trouble code that indicates: Internal Mode Switch Circuit 'A' Low
What causes a P1820 error code?
The most common causes of P1820 include: Malfunction of the internal mode switch; Open or short circuit in switch circuit; Poor contact in circuit connectors; Problems with power or circuit ground.
How do I fix a P1820 diagnostic trouble code?
To fix P1820: Check the integrity of the mode switch circuit. Check connections and contacts in connectors. Check voltage and ground in the circuit. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P1820?
Limited driving only, diagnose soon
How much does it cost to fix P1820?
The estimated repair cost for P1820 is $17–89. Actual cost depends on your vehicle, location, and labor rates.
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