P28B9 — Cylinder 11 Ion Current Sense Circuit Range/Performance

What Does P28B9 Mean?

P28B9 is a diagnostic trouble code indicating: Cylinder 11 Ion Current Sense Circuit Range/Performance. This code relates to the powertrain system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.

Symptoms of P28B9

⚠️ Check Engine Light (MIL) illuminated
⚠️ Cylinder 11 Ion Current Sense not operating within expected parameters
⚠️ Reduced efficiency or performance of related system
⚠️ Reduced engine performance

Common Causes

🔍 Cylinder 11 Ion Current Sense degraded or contaminated
🔍 Mechanical wear or binding in Cylinder 11 Ion Current Sense
🔍 Incorrect Cylinder 11 Ion Current Sense installed (wrong part number)
🔍 Related system mechanical issue affecting Cylinder 11 Ion Current Sense readings

Frequently Asked Questions

What does P28B9 mean?

P28B9 indicates: Cylinder 11 Ion Current Sense Circuit Range/Performance. The vehicle's computer has detected that the Cylinder 11 Ion Current Sense is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P28B9?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P28B9 for extended periods may cause additional problems.

How much does it cost to fix P28B9?

Repair costs for P28B9 typically range from $50 to $250, depending on the root cause. Simple wiring or connector repairs are on the lower end, while component replacement costs more. A proper diagnosis ($80–$150 at most shops) will identify the exact cause before committing to expensive parts.

What To Do Next

Possible Fixes

🔧 Inspect and clean Cylinder 11 Ion Current Sense
🔧 Replace degraded Cylinder 11 Ion Current Sense
🔧 Check for related mechanical issues affecting readings

1
Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

P28B9: Cylinder 11 Ion Current Sense Circuit Range/Performance