P0525
Cruise Control Servo Control Circuit Range/Performance
- Severity
- Low
- Driving
- No driving restriction
The cruise control servo circuit is electrically sound but the servo is not holding the throttle where it was told. Expect the car to surge, drift off the set speed, or cancel on its own. A vacuum leak in the servo or its hoses is the usual reason.
Possible causes
- CommonFailed vacuum or vent solenoid
- CommonSplit, perished or disconnected vacuum hose
- CommonCorroded connector or damaged wiring
- PossibleFailed vacuum supply - a leaking non-return valve or a weak vacuum pump
- PossibleFailed cruise control servo
- RareFailed control module driver
What you might notice
- Cruise control will not hold a speed
- Cruise control drifting or surging
- Cruise control cancelling on its own
- Cruise control will not engage
- Check engine light on
What to check, in order
- Check the vacuum hoses first. On a vacuum-operated cruise system a perished or disconnected hose is the most common cause and the cheapest to fix.
- Measure the solenoid winding resistance against specification.
- Inspect the connector for corrosion.
- Check the vacuum supply and its non-return valve.
- Confirm ordinary driving is unaffected before deciding how urgent this is.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Vehicle speed control, idle control and auxiliary inputs
P0500P0501P0502P0503P0504P0505P0506P0507P0508P0509P0510P0511P0512P0513P0514P0515P0516P0517P0518P0519P0520P0521P0522P0523P0524P0525P0526P0527P0528P0529P0530P0531P0532P0533P0534P0535P0536P0537P0538P0539P0540P0541P0542P0543P0544P0545P0546P0547P0548P0549P0550P0551P0552P0553P0554P0555P0556P0557P0558P0559P0560P0561P0562P0563P0564P0565P0566P0567P0568P0569P0570P0571P0572P0573P0574P0575P0576P0577P0578P0579P0580P0581P0582P0583P0584P0585P0586P0587P0588P0589P0590P0591P0592P0593P0594P0595P0596P0597P0598P0599