P28B0

Code

Generic P — Powertrain

Cylinder 9 Ion Current Sense Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 21 EN: 31 RU: 23

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Read and record freeze frame and all stored codes with a scan tool; note related misfire or ignition codes
Visual inspection: check coil, spark plug, boot, connector and wiring for damage, corrosion or oil/fuel contamination
Wiggle test harness with engine running (if safe) and watch live ion-sense data for intermittent change
Use scan tool or oscilloscope to view ion current waveform for cylinder 9 and compare with a known-good cylinder
Check continuity and resistance of wiring from coil connector to the ECM; inspect grounds and reference voltages
Swap the coil/ion-sensor assembly from cylinder 9 with another cylinder and see if the fault follows the coil

Expected behavior: ion current pulses synchronized with ignition events; baseline near zero when cylinder not ionized
Typical pulse amplitude: low-voltage signal (millivolt to low-volt range); spike present around combustion/ignition event
Timing: pulses occur shortly after ignition event and correspond to the cylinder's crank angle position
Fault signatures: no pulses, flatline, constant DC offset, excessive noise, or shorted/rounded pulses indicate wiring/coil/sensor issues

Retrieve freeze frame and related codes; record conditions when fault set.
Clear codes and attempt to reproduce. If intermittent, monitor live data during a drive cycle.
Perform a visual inspection of the cylinder 9 coil/ion sensor, connector, spark plug and wiring for obvious damage or contamination.
Using a scan tool or oscilloscope, capture the ion current waveform for cylinder 9 and compare to a known-good cylinder (look for timing, amplitude and shape).
Check connector pins for corrosion, bent pins, or poor contact; repair as needed and recheck.
Measure continuity/resistance between the coil ion-sense terminal and the ECM input pin; verify proper ground and any reference voltages per vehicle data.
Swap the cylinder 9 coil/ion-sensor assembly with another cylinder’s assembly. If the code follows the coil, replace the coil/module.
Inspect and, if necessary, replace the spark plug (correct gap and type). Clean carbon deposits in the plug well if present.
If wiring harness damage is found, repair or replace the affected section and protect against future chafing/contamination.
If wiring, connector and ignition components test OK and problem persists, consider ECM input circuit testing or ECM reflash/replacement only after confirming external circuitry good.
After repairs, clear codes and perform a drive cycle to confirm the fault does not return and that engine runs normally.