P0959Generic code

P0959 Code: Auto Shift Manual Mode Circuit Intermittent

The P0959 code means the signal from the manual mode circuit keeps dropping out or jumping. Manual mode may work only some of the time. It is nearly always a loose connection or a damaged wire, found by wiggling the harness.

Severity
Low
Can I keep driving?
Yes, no immediate risk
Estimated cost
$30 to $300
Difficulty
Medium
System
Transmission
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0959 code means

A switch tells the computer that the driver has selected the manual (sequential) mode of the gearbox.

It is a plain switch: the computer sees a high or a low voltage depending on its position. The P0959 code is an intermittent fault. These dropouts almost always come from a loose connection or a damaged wire.

When the signal fails, the gearbox does not go into manual mode, or it drops out of it for no reason.

You find an intermittent fault by making it happen. With the engine running and the scan tool in graph mode, move the wiring harness one section at a time, tap the connector gently and, if needed, warm the area with a hair dryer or spray the connector with water. The spot where the reading jumps is where the fault is.

P0959 code symptoms

  • Check engine light on.
  • Manual mode that does not work.

Likely causes of the P0959 code

  1. Loose connector contact. Pins that are loose or pushed back out of the housing.
  2. Wire broken inside the insulation. It opens the circuit when the car vibrates.
  3. Harness rubbing against moving or hot parts.
  4. Sensor with an intermittent fault, often one that shows up only when it heats up.

How to diagnose the P0959 code step by step

  1. Read the switch value on the scan tool and watch for sudden jumps.
  2. Inspect the connector for corrosion, water or loose pins.
  3. Check the supply and ground with the key on: the reference should be correct and the ground should drop less than 0.1 volt.
  4. Measure the signal with the connector plugged in and see whether it changes when you move the lever.
  5. Do the wiggle test on the harness with the scan tool in graph mode.
  6. Check continuity of each wire to the computer, which should be under 1 ohm.

How to fix the P0959 code

  • Repair the connector or the wiring.
  • Replace the switch if the tests confirm it drops out.
  • Correct the real condition if there is one.
  • Clear the P0959 code and verify with a road test.

Technical reference data

  • Switch in the lever.
  • Reference values only: check the manufacturer data for your vehicle.

Brand-specific notes

This code is common on levers that are dirty or have had liquid spilled into them, since a contaminated switch can make and break contact at random.

Frequently asked questions about P0959

Can I drive with a P0959 code?
Yes, with caution. The car normally keeps running, but manual mode may cut in and out.
Does the sensor have to be replaced?
Only if the tests confirm it. The connector and the wiring fail just as often as the switch does.
What does the manual mode of the gearbox do?
A switch tells the computer that the driver has selected the manual (sequential) mode of the gearbox.
How much does it cost to fix P0959?
As a rough guide, between $30 and $300. Most of the labor goes into finding the loose spot.
What does the P0959 code mean?
It means the manual mode signal is cutting out or jumping at random, so the computer cannot rely on it.
Will a P0959 code clear itself?
The light may go out when the fault stops showing, but an intermittent connection usually returns. Find the bad contact instead of just clearing it.

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Questions about the P0959 code

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