P0929Generic code

P0929 Code: Gear Shift Lock Solenoid Control Circuit Range/Performance

The P0929 code means the shift lock solenoid responds electrically but the result is not what the computer expects. The shifter may not come out of Park. A multimeter will not find this one, so compare what the solenoid does against what it was commanded to do.

Severity
Medium
Can I keep driving?
Yes, but with caution
Estimated cost
$40 to $400
Difficulty
Medium
System
Transmission
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0929 code means

The shift lock solenoid keeps the lever from moving out of Park (or the shift mechanism from moving) unless the safety conditions are met, normally with the brake pedal pressed.

The computer monitors the control circuit through its own driver transistor. The P0929 code is set when the component responds electrically but the result is not what is expected. Before you replace the component, check the fuse, relay, connector and wiring, because those are the most common causes.

If it fails, the lever may not come out of Park, or it may not lock at all. Many shifters have a manual emergency release. After any repair of these components you must run the transmission relearn procedures with a scan tool (clutch touch point, select and shift positions). Without them the transmission will not work properly.

This kind of fault is not usually solved with a multimeter, because electrically everything looks correct. You have to compare what the part reports with reality: use a pressure gauge, a thermometer or a tachometer, or command the component with the scan tool and watch whether the physical result matches the order.

P0929 code symptoms

  • Check engine light or another warning light on.
  • The shifter will not come out of Park.
  • The transmission does not engage gears or stays in neutral.
  • Transmission or engine warning light on.
  • Beep or warning message in the instrument cluster.

Likely causes of the P0929 code

  1. Worn or leaking actuator. The most frequent cause.
  2. Stiff transmission mechanism or one with play. Forks, synchronizers or linkage.
  3. Relearn procedures not done after a repair.
  4. Low supply voltage. Electric actuators draw a lot of current.

How to diagnose the P0929 code step by step

  1. Command the component with the scan tool and check whether it responds.
  2. Check the fuse and the relay. Measure voltage on both sides of the fuse, and swap the relay with an identical one.
  3. Measure the supply at the connector. You should see battery voltage with the key on or when the component is commanded.
  4. Measure the resistance of the component and compare it with the manual. Also check its insulation to ground.
  5. Check the control wire. Confirm continuity all the way to the computer and make sure there is no short.
  6. Activate the actuator with the scan tool and see whether it moves.
  7. Run the transmission relearn procedures after any repair.
  8. Measure battery voltage during activation. It should not fall below 11 volts.

How to fix the P0929 code

  • Repair the connector, the wiring or the power supply.
  • Replace the shift lock solenoid if it does not respond even with correct power and control signals.
  • Clear the codes and verify the repair.

Technical reference data

  • Electric actuator (DC motor) or a hydraulic solenoid valve controlled by a PWM signal.
  • Minimum battery voltage during activation: about 11 volts.
  • Approximate values only: check the manufacturer data for your vehicle.

Brand-specific notes

This code is very common on automated manual transmissions. On many hydraulic systems the actuator fluid is a specific type and the reservoir should be checked regularly.

P0929 on Opel

Very common on the Opel Easytronic.

P0929 on Fiat

Very common on the Fiat Dualogic.

P0929 on Toyota

Very common on the Toyota MMT.

P0929 on Smart

Seen on Smart vehicles with an automated manual transmission.

P0929 on BMW

Very common on the BMW SMG.

Frequently asked questions about P0929

Can I drive with a P0929 code?
Only with caution and only as far as the shop. The transmission can lose its gears at any moment.
What does the shift lock solenoid do?
It keeps the lever from moving out of Park, or the shift mechanism from moving, unless the safety conditions are met, normally with the brake pedal pressed.
Do I always have to replace the part?
No. Check the fuses, relays, connectors and wiring first. They are the usual causes and cost much less than a new solenoid.
How much does it cost to fix P0929?
As a rough guide, between $40 and $400. A relearn and a battery check are at the low end, and a solenoid replacement costs more.
What does the P0929 code mean?
The P0929 code is a generic OBD2 code that means the shift lock solenoid responds electrically but not with the result the computer expects.
Will a P0929 code clear itself?
Not if the solenoid is worn or the mechanism is stiff. The computer will see the poor response again and the code will come back.
What is the most common cause of P0929?
A worn or leaking actuator. A stiff mechanism, skipped relearns and low supply voltage come next.

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