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 sensor that checks the spark in cylinder 8. It's like a sensor is saying 'Hey, the spark here is too high!'
The ion current sensing circuit monitors the spark plug's ionization current to ensure proper combustion. A 'high' signal indicates an abnormal condition in the circuit for cylinder 8.
The P28AF code is triggered when the Engine Control Module (ECM) detects a high voltage condition in the ion current sensing circuit for cylinder 8. This circuit is responsible for monitoring the ionization current in the spark plug to ensure proper combustion and ignition timing. A high signal may indicate a fault in the circuit, wiring, or the spark plug itself.
• Check Engine Light is on
• Engine misfire
• Poor fuel economy
• Rough engine idle
• Faulty spark plug in cylinder 8
• Damaged wiring or connectors in the ion current circuit
• Faulty ignition coil for cylinder 8
• Defective ECM
ECM: Engine Control Module
Ionization: The process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons.
• Use an OBD-II scanner to confirm the code.
• Inspect the spark plug and ignition coil for cylinder 8.
• Check the wiring and connectors for damage or corrosion.
• Test the ECM for faults.
• Replace the spark plug in cylinder 8.
• Repair or replace damaged wiring or connectors.
• Replace the ignition coil for cylinder 8.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Spark plug socket
• Wrench set
$150 - $500
Moderate
• Chevrolet Silverado
• Ford F-150
• Dodge Ram 1500
• Regularly inspect spark plugs and ignition coils.
• Perform routine vehicle maintenance.
• Check and clean electrical connectors.
Sensor Issue
• Avoid driving the vehicle until the issue is resolved to prevent further damage.
• Consult with a professional mechanic for accurate diagnosis and repair.
Check with your vehicle manufacturer for warranty coverage on ignition system components.
This code is commonly associated with ignition system failures and has been reported in vehicles with high mileage.
Moderate – Addressing this issue promptly can prevent further engine damage.
Driving with a misfire can lead to increased emissions and potential damage to the catalytic converter.
• Engine at operating temperature
• Vehicle in park or neutral
The ion current sensor is typically integrated into the ignition coil or near the spark plug of cylinder 8.
Q: What happens if I ignore this code?
A: Ignoring this code can lead to engine misfires, reduced fuel efficiency, and potential damage to the catalytic converter.
Q: Can I drive with a P28AF code?
A: It's not recommended to drive with this code active, as it can cause further engine damage.
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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.