Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
The car's computer has detected a problem with the spark plug or coil in cylinder number 5, which helps the engine run smoothly.
The ion sensing ignition system detects misfires by measuring the ion current in the combustion chamber. A fault in this system for cylinder 5 triggers the P1389 code.
The P1389 code indicates an issue with the ion sensing circuit in the ignition coil for cylinder 5. This system uses the ion current measurement to detect combustion quality and misfires. A fault here can lead to engine performance issues.
• Engine misfire
• Rough idling
• Reduced fuel efficiency
• Faulty ignition coil in cylinder 5
• Damaged or corroded wiring or connectors
• Faulty spark plug in cylinder 5
Ignition Coil: A component that converts the battery's voltage to a higher voltage to create a spark in the spark plugs.
Ion Sensing: A method used to detect combustion quality and misfires by measuring ion current.
• Inspect the ignition coil and spark plug for cylinder 5.
• Check the wiring and connectors for damage or corrosion.
• Use an OBD-II scanner to confirm the code and clear it to see if it returns.
• Replace the faulty ignition coil.
• Replace the spark plug in cylinder 5.
• Repair or replace damaged wiring or connectors.
• OBD-II scanner
• Multimeter
• Socket wrench set
$150 - $300
Moderate
• Toyota Camry
• Honda Accord
• Ford F-150
• Regularly inspect and replace spark plugs.
• Ensure ignition coils are in good condition.
• Check wiring and connectors for corrosion.
Engine Performance
• Do not ignore the check engine light.
• Have your vehicle inspected by a professional if unsure.
Check your vehicle's warranty; ignition components may be covered.
This code is often associated with ignition coil issues, particularly in vehicles with ion sensing systems.
Moderate – Should be addressed soon to prevent further engine damage.
Driving with a misfire can lead to increased emissions and potential engine damage.
• Engine running
• Vehicle at operating temperature
The ignition coil for cylinder 5 is located on the engine, typically above the spark plug for that cylinder.
Q: Can I drive with a P1389 code?
A: It's not recommended as it can cause further engine damage.
Q: How can I prevent this code from appearing?
A: Regular maintenance of ignition components 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.
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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.