Error code

OBD2 P0790

OBD2P0790
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Normal/Performance Switch Circuit.

Severity

moderateCan drive but may experience shifting issues and reduced performance.

Summary

P0790 indicates an issue with the transmission mode selection switch circuit malfunction, which affects how the transmission range is selected and communicated to the PCM/TCM.

Symptoms

  • Malfunction Indicator Lamp (MIL) lights up
  • Torque converter clutch may not function properly
  • Overdrive light may flash in some applications
  • Vehicle may enter 'limp-in' mode with harsh shifts

Common Causes

  • Water contamination of the transmission mode switch
  • Open or shorted electrical wiring, damaged, corroded, or disconnected wiring or connectors

Diagnosis

  1. Inspect the transmission mode selection switch for water contamination.
  2. Check electrical connections and wiring for damage, corrosion, or disconnection.

Fixes

  • Replace damaged or contaminated components such as the transmission mode selector switch or faulty wiring.

FAQ

What should I do if my MIL light comes on with P0790?

Inspect and repair any water damage to the transmission mode selection switch, check for damaged or disconnected electrical connections.

Can I drive with a P0790 code?

You can drive but may experience shifting issues and reduced performance. It's recommended to address the issue promptly.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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