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Symptom

Vehicle rolls when parked

The car moves after being left in Park — the most serious symptom in the transmission range, and the rarest.

Park is a mechanical lock, not a brake. A steel pawl drops into a toothed wheel on the output shaft and physically prevents it turning. When it works there is nothing to feel; when it does not, there is nothing to feel either — which is why a rollaway is usually the first evidence.

Shift-by-wire is why this is now an electrical fault as well as a mechanical one. With no cable from the lever to the gearbox, a motor moves the pawl and sensors report whether it engaged. A fault in that chain can leave the car in neutral while the display says P.

The habit that removes the risk entirely costs nothing: always apply the parking brake, every time, before selecting P. Doing it in that order also takes the vehicle's weight off the pawl, which is why a car parked on a slope is sometimes reluctant to come out of Park — the pawl is loaded against the tooth.

On a hill, turn the front wheels into the kerb as well. If the car has rolled once, do not park it on any gradient until it has been diagnosed.

Also described as: car rolled away, rolls in park, park not holding, vehicle moves in park, rollaway, wont stay in park, در پارک سر میخورد, ماشین در شیب حرکت میکند, se mueve aparcado, rueda estando en parking, no queda quieto aparcado, السيارة تتحرك وهي راكنة, تزحف على البارك, ما تثبت وهي واقفة

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Some causes mean you should stop driving

1 of the 35 codes that produce this symptom indicate a fault where continuing to drive risks damage or is unsafe. If the symptom is sudden or severe, treat it as one of those until a scan says otherwise.

What this usually means

This is the most serious symptom in the transmission range and the rarest. If the car has rolled once, do not park it on any gradient until it has been diagnosed.

Park is a mechanical lock, not a brake. A steel pawl drops into a toothed wheel on the output shaft and physically prevents it turning. When it works there is nothing to feel; when it does not, there is nothing to feel either — which is why a rollaway is usually the first evidence anybody gets.

Shift-by-wire is why this is now an electrical fault as well as a mechanical one. With no cable from the lever to the gearbox, a motor moves the pawl and sensors report whether it engaged. A fault anywhere in that chain can leave the car in neutral while the display says P, and the display is not confirmation — it is the module's belief.

The habit that removes the risk entirely costs nothing: always apply the parking brake, every time, before selecting P. Doing it in that order also takes the vehicle's weight off the pawl — which is why a car parked on a slope is sometimes reluctant to come out of park, the pawl being loaded against a tooth. On a hill, turn the front wheels into the kerb as well.

The mechanical failures are a broken or worn pawl, a stretched or maladjusted selector cable, or a pawl that never fully engages because the lever does not reach its detent. A lever that feels vague at the P end, or that needs to be held, is reporting exactly that.

Working through it

  • Car rolled with the display showing P

    Likely cause
    The pawl did not engage — mechanically, or because the actuator never moved it on a shift-by-wire selector
    How to confirm it
    Do not reproduce it on a slope. Read selector and transmission codes, and compare commanded against actual park state where the tool exposes it.
    What fixes it
    Repair the named fault before the vehicle is used. Apply the parking brake without exception meanwhile.
  • Lever feels vague at the P end, or must be held

    Likely cause
    Selector cable stretched or out of adjustment — the pawl never reaches full engagement
    How to confirm it
    Compare lever position against reported position, and check cable adjustment at the transmission end.
    What fixes it
    Adjust or renew the cable. This is the commonest mechanical version and it is cheap.
  • A distinct clunk when selecting P, and the car settles noticeably

    Likely cause
    Normal — the pawl dropping in and the weight settling against it, especially on a slope
    How to confirm it
    Applying the parking brake first removes it, because the weight is already held.
    What fixes it
    No repair. Change the order: parking brake first, then P.
  • Reluctant to come out of P on a slope

    Likely cause
    The pawl is loaded against a tooth by the vehicle's weight — normal, and a sign the habit above is not being used
    How to confirm it
    Release by rocking slightly with the brake pedal pressed. It confirms loading rather than a fault.
    What fixes it
    No repair. Apply the parking brake before selecting P and it stops happening.
  • Shift-by-wire selector, park state uncertain, warnings displayed

    Likely cause
    The actuator, its position sensor, or the module — the display shows belief rather than confirmation
    How to confirm it
    Read codes from the selector and transmission modules. Never treat the P on the display as evidence the pawl is in.
    What fixes it
    Repair as the codes name. Treat the vehicle as unparked until it is fixed.
  • Rolled with an electric parking brake that had reported a fault

    Likely cause
    Two systems both unable to hold the car — the parking brake fault made the pawl the only restraint
    How to confirm it
    Read the parking brake module as well. A car with a faulty electric parking brake should never have been left relying on either.
    What fixes it
    Repair both. Chock a wheel and select a gear meanwhile if the vehicle must be left at all.

Codes that produce this symptom (35)

Listed with the codes that most typically present this way first — the likeliest place to start.

Information, not instruction

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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.

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