P28B5

Code

Generic P — Powertrain

Cylinder 10 Ion Current Sense Circuit Range/Performance

Brand: Generic

Type: P — Powertrain

Views: UK: 40 EN: 48 RU: 22

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Read and record freeze frame and all stored codes; note related misfire or fuel trim codes
Visually inspect coil, spark plug, wiring harness and connectors for cylinder 10
Check for corrosion, bent pins, damaged insulation, or water ingress at connectors
Compare cylinder 10 ignition components with a known-good cylinder
Use a scan tool to view live ion-current or ion-sense parameter and compare to another cylinder
Perform coil-swap (swap coil from cylinder 10 with another cylinder) and see if code follows

Ion-current pulses occur synchronized with the ignition event; expected short-duration pulses after spark
Typical ion-current magnitude: very small currents (microamp to low milliamp range) that vary with combustion quality
Signal baseline should be low (near zero) between events; no sustained leakage or offset
Pulse timing corresponds to ignition dwell/spark window for that cylinder
Excessive noise, absent pulses, very low amplitude or continuous leakage indicate problem

Retrieve freeze frame, related codes and live data. Note conditions when fault set (rpm, load, temp).
Visually inspect spark plug, coil, harness and connectors for cylinder 10. Repair obvious damage/corrosion.
Clear codes and attempt to reproduce. If intermittent, perform road test under similar conditions.
Swap the coil/igniter assembly from cylinder 10 with a known-good cylinder. If code follows the coil, replace the coil/igniter.
Swap spark plug to a known-good plug or inspect/replace plug if fouled or damaged.
Using an oscilloscope or manufacturer-specified scan tool, monitor the ion-current waveform at the ECM input and compare to a good cylinder. Look for expected pulse amplitude, shape and timing.
Check wiring continuity/resistance between coil/igniter and ECM ion-sense input; check for shorts to power or ground and for proper grounds.
Inspect and test the fuel injector, compression and valve condition for cylinder 10 if ion signal amplitude is low despite good ignition hardware.
If wiring and components test good and the ion-sense waveform is abnormal only at the ECM, suspect ECM input circuit fault or software; consult manufacturer repair information before ECM replacement.
After repairs, clear codes and verify good ion-current waveforms and no recurrence of P28B5 during the same operating conditions.