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P1801

Performance Selector Switch Failure.

  • Buick
  • Powertrain
  • Manufacturer code
  • Low severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
8
AreaTransmission
01
FaultThe specific fault in that area

What it means

P1801 on a Buick means the control module has detected a fault in the performance (shift mode) selector switch circuit. This is the switch that lets the driver choose between modes such as normal, performance or economy shift patterns. The module saw a signal from the switch that was out of range, missing or illogical for the selected position.

Symptoms

  • Check engine or service light on
  • Performance, economy or shift mode selector not working
  • Gearshifts feel harsher, softer or later than usual
  • Transmission stuck in one shift mode
  • Possible reduced or default shift behaviour

Possible causes

  • Faulty performance selector switchlikely
  • Damaged, chafed or corroded wiring to the switchlikely
  • Loose, corroded or water-affected connector at the switch or control modulelikely
  • Poor earth or supply to the switch circuitpossible
  • Blown fuse feeding the switch or related circuitpossible
  • Fault in the powertrain or transmission control modulerare

How to diagnose

  1. Read all stored codes and freeze frame data, noting whether the code is current or history and whether other transmission codes are present
  2. Operate the selector switch through every position and watch whether the scan data for the switch state changes correctly
  3. Check the relevant fuses and look for any history of spilt drinks or water ingress around the switch
  4. Inspect the switch, its connector and the wiring for damage, chafing, corrosion or bent pins
  5. Check the switch circuit for supply, earth and signal voltage against the model-specific wiring diagram
  6. Test the switch resistance or continuity in each position against the manufacturer's specification, as values vary by model
  7. Wiggle-test the harness with the switch state displayed to find intermittent faults
  8. Only after the wiring and switch are proven good, consider testing the control module and check for any applicable software updates

How to fix

  • Replace the performance selector switch if it fails its tests
  • Repair or replace damaged wiring in the switch circuit
  • Clean or replace corroded or damaged connectors and terminals
  • Restore a poor earth or supply connection
  • Replace a blown fuse once the cause of the overload is found
  • Repair or replace the control module, or update its software if a known fault is confirmed, as a last resort

Can I keep driving?

Low severity

The car can normally be driven as the fault mainly affects shift mode selection, though shift quality may be affected. Book it in for diagnosis soon, and stop if the gearbox starts to behave erratically.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

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