P2898

Code

Generic P — Powertrain

Cylinder 3 Ion Current Sense Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 23 EN: 37 RU: 21

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Page language: EN

Causes

Open, short, or high-resistance wiring to the ion-sense circuit for cylinder 3
Poor connector pin contact, corrosion, or water ingress at coil/plug/harness
Faulty ignition coil or coil pack for cylinder 3
Damaged or fouled spark plug in cylinder 3
Faulty PCM/ECM or internal ion-sense circuitry
Aftermarket ignition components interfering with the ion-sense signal

Symptoms

Check Engine MIL illuminated
Engine misfire on cylinder 3 or random/continuous misfire, rough idle
Reduced engine power, hesitation or poor acceleration
Increased fuel consumption and higher emissions
Failed emissions readiness or failed OBD2 test
Intermittent misfire or hard start in some cases

What to check

Scan for stored and pending DTCs; record freeze-frame and live data focusing on ion-sense and misfire counters
Visually inspect wiring, connectors, and coil/plug area for damage, corrosion or contamination
Backprobe the ion-sense connector and measure voltage/waveform with a scope while cranking/running
Check continuity/resistance between ECM pin and coil/connector; check for short to battery or ground
Swap cylinder 3 coil with another cylinder’s coil (if identical) and see if the code/fault follows
Inspect and/or replace spark plug for cylinder 3; verify correct gap and condition

Signal parameters

Idle/rest baseline: near 0 V (small offset) or very low current; expected near sensor ground reference
Combustion pulse: short duration pulse(s) correlated to ignition events; typically small voltage pulses (approx. 0.2–2.5 V depending on design) or microamp–milliamp ion current signals
Timing: pulses should occur synchronized with cylinder 3 ignition events and vary with RPM/load
Failure modes: open circuit shows no pulses; short to battery may show flat high voltage; short to ground may clamp signal near 0 V
Use an oscilloscope for waveform verification — look for consistent, repeatable pulses per ignition cycle

Diagnostic algorithm

Retrieve and record all trouble codes and freeze-frame data. Confirm P2898 is current and note any related misfire or ignition codes (e.g., P0303, P0353).
Visually inspect coil pack, spark plug, harness and connectors at cylinder 3 for damage, corrosion, oil or water intrusion. Repair any obvious issues.
With ignition off, unplug coil/pack connector and inspect pins for corrosion, bent pins or poor contact. Reconnect and secure.
Verify power and ground to the coil/ion-sense module (key ON). Measure reference voltages per factory data. Repair power/ground faults.
Backprobe the ion-sense signal wire at the coil/connector and at the ECM plug. Check continuity and resistance to ECM pin; check for shorts to battery or ground. Repair wiring as needed.
Use a lab scope to capture the ion-sense waveform during cranking and running. Confirm pulses occur for cylinder 3 and compare to a known-good cylinder. Note amplitude, shape and timing.
Swap cylinder 3 ignition coil with a known-good identical coil from another cylinder. If the fault follows the coil, replace the coil.
Inspect and/or replace the spark plug in cylinder 3. Re-test if necessary.
If wiring, coil and plug check good but no valid signal is present, consider ECM input failure. Before ECM replacement, re-check wiring harness, ground integrity, and consult manufacturer service bulletins and wiring diagrams.
Clear codes and test-drive to confirm repair. Verify readiness and that P2898 does not return.

Likely causes

Damaged wiring or connector to cylinder 3 ion-sense input (broken wire, chafing, corrosion)
Failed ignition coil for cylinder 3 (open/shorted primary or secondary or internal electronics)
Fouled, cracked, or improperly gapped spark plug in cylinder 3
Poor ground or power supply to the ignition module/coil pack
Contaminated connector (oil/water) causing intermittent signal
ECM input circuit fault (less common)

Fault status

⚠️ Status

Engine control detected an abnormal or missing ion-current signal from cylinder 3. This can be caused by wiring/connectors, the ignition coil, spark plug, contamination, or less commonly a PCM input fault. Expect possible rough idle, misfire, or reduced performance until the underlying issue is corrected.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours