Code
P2325
Generic
P — Powertrain
Ignition Coil I Primary Control Circuit High
AI status
Completed
Completed
100%
Causes
- Open or high-resistance ground in coil primary/driver circuit
- Short to battery positive (B+) in coil primary wiring
- Faulty ignition coil (internal short or open in primary winding)
- Faulty ignition driver in PCM or external ignition module
- Corroded or loose connector/pins at coil or PCM
- Aftermarket device or incorrect component installation affecting coil circuit
Symptoms
- MIL (Check Engine Light) illuminated
- Engine misfire on affected cylinder or rough idle
- Hard start or no-start condition (if driver or coil failed completely)
- Reduced engine performance or hesitation under load
- Intermittent misfires or stumble that may change with vibration
What to check
- Read freeze frame and freeze-frame parameters to confirm conditions present when code set
- Scan for related codes (misfire P03xx, other coil circuit codes P035x, battery/charging faults)
- Visually inspect coil, connector and wiring for damage, corrosion, pin push-out or heat damage
- Back-probe coil primary terminal with key ON and during cranking to observe voltage behavior
- Measure coil primary resistance with meter (compare to spec)
- Check continuity from coil low-side terminal to PCM driver and check for shorts to B+ or ground
Signal parameters
- Key ON, engine OFF: control circuit may read near battery voltage (open/high) until driver commands ground
- When driver commanded ON: primary control circuit ≈ 0 V (saturated low-side) — typical
- When driver commanded OFF: circuit should return to battery voltage (~11–15 V depending on charging)
- Coil primary resistance: vehicle-specific (commonly ~0.3–3 Ω) — consult OEM spec
- Dwell/current and pulse width are engine-specific; primary waveform should show a defined grounded pulse when firing
Diagnostic algorithm
- Confirm vehicle and code history; note symptoms and whether code is continuous or intermittent
- Check battery voltage and charging system; low supply voltage can confuse diagnostics
- Visually inspect coil I connector and wiring for corrosion, bent pins, melted insulation or loose terminals
- Unlock and wiggle connectors and harness while monitoring live data or watching voltage—look for intermittent changes
- Back-probe the coil primary control wire: with key ON and during cranking, verify voltage goes low when PCM commands coil ON and returns to battery voltage when OFF
- If coil never commands low, disconnect the coil and re-test to determine if the wiring/PCM still shows the high condition
- Measure coil primary resistance and compare to specification; replace coil if out of range or internally shorted
- Check for short to battery: with coil disconnected, measure resistance between coil control wire and B+ and to ground to find abnormal shorts
- If wiring checks OK, test PCM/ignition module driver output with an oscilloscope (safe reference method) or substitute a known-good coil if available
- Repair damaged wiring or connectors, replace faulty coil or ignition module/PCM as indicated, clear codes and road test to confirm repair
Likely causes
- Broken or corroded coil harness connector pin
- Short to B+ on the coil low-side wire
- Failed coil internal electronics causing abnormal voltage reading
- Damaged/failed PCM ignition driver transistor
- Poor ground at engine/chassis near coil
Fault status
Status
Ignition Coil I Primary Control Circuit High — PCM detected higher-than-expected voltage on coil I primary control circuit (circuit high).
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
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