P0959: Auto Shift Manual Mode Circuit Intermittent

The signal reporting the selector lever in the manual gate drops out or toggles briefly while the lever is not moved, so the transmission control switches between manual and automatic mode on its own. The voltage is not stuck out of range as with P0957 or P0958 but jumps. Loose connector pins at the lever, a harness that flexes with the shifter or a worn microswitch are typical. A Hyundai patent shows such a microswitch actuated by the lever's sideways movement, a Nissan patent the two-contact mode switch. No manufacturer documents this exact code publicly; CARB requires circuit checks. P0955 is the general fault, P0954 the intermittent fault of the up/down circuit.

Medium severity. Can I keep driving?Drive as little as possible and gently. If the transmission slips or stays in one gear, go slowly to a repair shop or call for a tow truck.

Symptoms

Manual mode switches on or off by itself
Gear display flickers between D and manual gear
Fault often appears on rough roads

Most likely causes

Loose pins in the selector lever connector
Worn or bouncing mode microswitch
Harness damaged where it moves with the lever

What to check, in order

Start with the simplest. You can tick off each step.

Check the fluid level and condition according to the manufacturer
Gently move the wiring with the engine running and watch whether the reading changes.
Check the transmission connector
Read the data with a transmission-compatible scanner
Measure the solenoid valve circuit
Leave opening the transmission to a specialized repair shop

Good to know

Repair difficulty: medium

What each character of P0959 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
9: Transmission
59: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0959?

Drive as little as possible and gently. If the transmission slips or stays in one gear, go slowly to a repair shop or call for a tow truck.

What causes code P0959?

The most common causes are: loose pins in the selector lever connector; worn or bouncing mode microswitch; harness damaged where it moves with the lever.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.