Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer has detected a problem with the part of the ignition switch that tells the car to start. It's like when a light switch doesn't work properly and the light won't turn on.
The P25B9 code is triggered when the vehicle's computer detects a higher than expected voltage in the auxiliary ignition switch's on/start position circuit.
The ignition switch is responsible for sending the correct signals to the vehicle's systems to start the engine and power accessories. The 'circuit high' condition indicates that the voltage in the circuit is above the normal range, which may be due to a short circuit, a faulty switch, or an issue with the wiring.
• Engine does not start
• Dashboard lights may not turn on
• No response when turning the key
• Faulty ignition switch
• Short circuit in the wiring
• Faulty relay or fuse
Ignition Switch: A device that activates the main electrical systems of a vehicle.
Circuit High: A condition where the voltage in a circuit is higher than expected.
• Check for any blown fuses related to the ignition system.
• Inspect the ignition switch for damage or wear.
• Test the wiring for shorts or open circuits.
• Replace the faulty ignition switch.
• Repair or replace damaged wiring.
• Replace any blown fuses or faulty relays.
• Multimeter
• Screwdriver set
• Wire strippers
$100 - $300
Moderate
• Vehicle 1
• Vehicle 2
• Vehicle 3
• Regularly inspect the ignition switch for wear.
• Ensure wiring is properly insulated and secured.
• Avoid excessive force when turning the ignition key.
Electrical Circuit Issue
• Avoid using excessive force on the ignition switch.
• Have the ignition system inspected regularly.
Check with your vehicle manufacturer for warranty coverage on electrical components.
This code has been associated with ignition switch failures in some vehicle models, prompting recalls or service bulletins.
High – This issue can prevent the vehicle from starting, leaving you stranded.
Driving with a malfunctioning ignition switch can lead to unexpected vehicle shutdowns, posing a safety risk.
• Vehicle in 'On' position but engine not running.
• Check voltage levels at the ignition switch.
The ignition switch is typically located on the steering column or dashboard, where the key is inserted.
Q: Can I drive with a P25B9 code?
A: It's not recommended as the vehicle may fail to start or shut down unexpectedly.
Q: How can I prevent this code from occurring?
A: Regular maintenance and gentle handling of the ignition switch can help prevent this issue.
Pro · Four-system diagnostics
A handheld scanner aimed at engine, transmission, ABS, and airbag diagnostic work.
Chassis and ABS faults usually need a scanner that can read brake-system data directly.
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Universal · Torque wrench
Useful when reassembly torque matters for wheel, suspension, and under-hood fasteners.
Useful when wheel, hub, or suspension hardware needs correct reassembly torque.
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Universal · Drive-on ramps
Helpful for safer access underneath the vehicle during exhaust, EVAP, and underbody inspection work.
Helpful for safer access during underbody inspection work.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.
Fitment Required · Vehicle-fitment part
Commonly relevant for misfire, ignition-efficiency, and some drivability-related repairs.
Misfire and ignition-related faults commonly involve spark plugs as part of the repair path.
Check the correct plug type, gap, and engine application for your vehicle.
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Fitment Required · Vehicle-fitment part
Relevant when the fault points toward ignition-coil performance or cylinder-specific ignition issues.
Some ignition faults involve coil performance or cylinder-specific coil problems.
Match the coil to your engine and confirm the failed component before ordering.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.