P28B6

Code

Generic P — Powertrain

Cylinder 10 Ion Current Sense Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 30 EN: 30 RU: 25

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or shorted ion-sense wiring or connector to cylinder 10
Faulty ignition coil or coil-on-plug for cylinder 10
Bad or fouled spark plug in cylinder 10
Missing or weak spark (ignition primary/secondary fault)
Injector not delivering fuel (no combustion in cylinder 10)
Low or no compression in cylinder 10 (mechanical issue)

Symptoms

MIL (Check Engine) illuminated
Rough idle or engine misfire, especially at low load
Reduced engine power or hesitation under acceleration
Poor fuel economy
Possible misfire diagnostic trouble codes logged for cylinder 10

What to check

Read freeze frame and live data with a capable scan tool; note misfire counts and ion-sense PID for cylinder 10
Visually inspect wiring, connectors and boots at coil/on-plug for damage, corrosion or loose pins
Swap coil (or coil pack) from cylinder 10 with a known good cylinder and see if the code follows
Inspect and measure spark plug condition; replace if worn, fouled or damaged
Verify injector operation (listen with stethoscope, measure pulse, or use noid light) and fuel delivery to cylinder 10
Perform a compression or leak-down test on cylinder 10 to rule out mechanical issues

Signal parameters

Ion-sense circuits are manufacturer-specific; typical monitored parameter is a pulsed voltage or current coincident with combustion
Expected: discernible ion/current pulses for firing events on a working cylinder; exact amplitude varies by system (commonly within a 0–5 V logic input range or microamp-level current after conditioning)
Fault condition: signal below threshold or no detectable combustion pulses for cylinder 10
Use OEM service information for exact thresholds, pinouts and test voltages for the ion-sense input

Diagnostic algorithm

Connect an advanced scan tool, record freeze frame and live data. Confirm code P28B6 and check for any accompanying misfire codes or P28B family codes.
Visually inspect the coil, coil wiring, ion-sense connector and spark plug boot at cylinder 10 for damage, oil, moisture or corrosion. Repair visible damage.
Swap the coil/ignition module from cylinder 10 with a known good cylinder. Clear codes and crank/run engine. If code moves to the other cylinder, suspect the coil/module.
Inspect and/or replace the spark plug in cylinder 10. If plug is fouled or damaged, replace and retest.
Verify injector operation for cylinder 10 (electrical pulse and fuel delivery). Repair or replace injector if not operating correctly.
Perform a compression or leak-down test on cylinder 10 to rule out mechanical causes (valve, piston, or head gasket issues). Address mechanical faults as required.
With ignition disabled for safety or using an oscilloscope with proper HV probe and grounding practices, probe the ion-sense input (or secondary ignition waveform) to confirm presence/absence of ion current pulses during attempted combustion. Compare to a good cylinder waveform.
Check continuity and resistance of the ion-sense wiring between the coil/connector and the ECM. Check for shorts to ground or 12 V and repair wiring as needed.
Inspect engine and ECM grounds; clean and tighten ground straps and battery connections.
If wiring, coil, spark plug, injector and mechanical tests are good and fault persists, consult OEM wiring diagrams and consider replacing the ECM or ignition control module only after confirming input circuits are correct and other components eliminated.

Likely causes

Damaged/poor connector or wiring on ion-sense lead to cylinder 10
Failed coil-on-plug or ignition module for cylinder 10
Bad spark plug or carbon-fouled plug preventing ion current
Injector malfunction or lack of fuel causing no combustion signal

Fault status

⚠️ Status

Cylinder 10 ion current sense circuit low — ECM detects no/low ion current or combustion signal on cylinder 10 input. Possible ignition, fuel, wiring, mechanical or ECM fault.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours