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 way it senses electrical signals in the third cylinder of the engine. It's like if your TV remote wasn't sending the right signals to the TV.
The ion current sense circuit monitors the combustion process in the cylinder by measuring the ionization current. A high signal indicates an abnormality in this process.
The P289B code is triggered when the powertrain control module (PCM) detects that the ion current sense circuit for cylinder 3 is reading higher than expected. This circuit is responsible for monitoring the ionization current, which helps in optimizing combustion and detecting misfires.
• Check Engine Light illuminated
• Engine misfires
• Poor fuel economy
• Faulty ignition coil
• Damaged or corroded wiring or connectors
• Defective spark plug
Ionization: The process of adding or removing electrons to create ions.
PCM: Powertrain Control Module, the computer that controls engine and transmission functions.
• Use an OBD-II scanner to confirm the code.
• Inspect the ignition coil and spark plug for cylinder 3.
• Check the wiring and connectors for damage or corrosion.
• Replace the ignition coil for cylinder 3 if faulty.
• Replace the spark plug if worn or damaged.
• Repair or replace any damaged wiring or connectors.
• OBD-II scanner
• Multimeter
• Socket set
$100 - $300
Moderate
• Toyota Camry
• Honda Accord
• Ford Focus
• Regularly inspect ignition components.
• Use high-quality fuel.
• Keep up with scheduled maintenance.
Sensor Issue
• Have the vehicle inspected by a professional.
• Avoid driving the vehicle aggressively until repaired.
Check if the ignition system components are covered under the vehicle's powertrain warranty.
This code has been associated with ignition system issues in various models, leading to misfire detection improvements.
Moderate – Should be addressed soon to prevent further engine issues.
Driving with a misfire can damage the catalytic converter and increase emissions.
• Engine running
• Vehicle at operating temperature
The ignition coil and spark plug for cylinder 3 are located on the engine, typically on the side or top of the cylinder head.
Q: Can I drive my car with a P289B code?
A: It's not recommended to drive for long distances, as it can cause further damage to the engine.
Q: How can I prevent this code from appearing?
A: Regular maintenance and using quality parts can help prevent this issue.
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Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
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Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
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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.