P2897

Code

Generic P — Powertrain

Cylinder 2 Ion Current Sense Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 17 EN: 25 RU: 18

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Page language: EN

Causes

Short to battery voltage or high-voltage bleed into the ion-sense circuit
Damaged or corroded ion-sense wiring or connector for cylinder 2
Faulty ignition coil or ignition module on cylinder 2
Contaminated, damaged, or improperly gapped spark plug
Excessive combustion ionization (pre-ignition, detonation, or oil/fuel contamination)
Poor ground or supply voltage issues

Symptoms

Malfunction Indicator Lamp (MIL/Check Engine) illuminated
Misfire or rough running on cylinder 2 or overall rough idle
Reduced engine power or drivability problems
Intermittent or consistent misfire-related symptoms under load
Possible engine knock/detonation symptoms if pre-ignition is present

What to check

Read freeze frame and live data with a capable scan tool; monitor ion-current (or ion-sense) reading for cylinder 2 and compare to other cylinders
Verify stored freeze-frame conditions and whether the code is current or historic
Visually inspect ion-sense wiring, connectors, and coil/plug area for damage, corrosion, oil, or melted insulation
Perform wiggle tests on connectors while monitoring live data to look for intermittent changes
Check battery voltage and engine grounds for proper connection and resistance
Inspect spark plug condition, gap, and torque for cylinder 2

Signal parameters

Ion current is an extremely small current measured after ignition; ECM converts it to a voltage or digital value
Code triggers when cylinder 2 ion-sense value is significantly higher than expected or exceeds the ECM threshold compared with other cylinders
Values are manufacturer-specific — consult service manual for absolute thresholds and expected waveform shape
Using an oscilloscope can show abnormal post-spark ionization waveform (higher amplitude or longer duration) on cylinder 2

Diagnostic algorithm

Retrieve freeze frame and DTC history. Confirm P2897 is active and note operating conditions when it set.
Visually inspect coil, spark plug, wiring harness, and connector at cylinder 2 for damage, oil, corrosion, or loose pins; repair or replace obvious faults.
Clear codes and attempt to re-create. Monitor ion-sense live data for cylinder 2 while cranking and during running to confirm abnormal high reading.
Perform a coil swap: move the cylinder 2 coil to another cylinder. If the high-ion reading (or DTC) follows the coil, replace the coil/ignition module.
Inspect and/or replace the spark plug on cylinder 2. Check plug gap, fouling, or electrode damage that could change ionization characteristics.
Check wiring continuity and resistance between the ion-sense input and the ECM pin; check for shorts to battery voltage and to ground. Repair wiring as needed.
Use an oscilloscope or a diagnostic tool capable of viewing ion-sense waveform to compare cylinder 2 to known-good waveform/patterns; look for higher amplitude or abnormal shape.
Check engine mechanical condition if indicated: compression or leak-down test to rule out mechanical issues that could change combustion and ionization.
Verify charging and ground system integrity. Repair poor grounds or unstable supply voltage.
If wiring, coil, and plug check out and the issue remains, consult manufacturer service information for ECM input testing and possible ECM replacement or reflash.

Likely causes

Wiring short to 12V at the ion-sense lead or connector
Failed ignition coil/driver for cylinder 2
Contaminated or damaged spark plug/electrode creating abnormal ion current
Oil fouling or excessive fuel causing abnormal ionization
Loose or corroded connector or poor ECM ground

Fault status

⚠️ Status

Cylinder 2 ion-current sense circuit reading higher than expected; possible short to voltage, ignition or plug fault, contamination, or ECM input fault. Further diagnosis required.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours