OBD-II Code · Powertrain
P2301
Ignition Coil "A" Secondary Circuit
Severity
medium
Worth booking. It costs fuel, emissions or comfort until it is fixed.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$50–$400
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
Secondary (high-voltage) side fault on cylinder 1 coil.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Misfire on cyl 1
- Check engine light
- Rough running
Likely causes
- Failed coilMost common
- Bad plug wire/boot
- Worn spark plug
Read the full diagnostic procedureP2301 means the PCM detected a high-voltage condition on the primary control circuit of ignition coil A — the IGT command line is reading higher than…
P2301 means the PCM detected a high-voltage condition on the primary control circuit of ignition coil A — the IGT command line is reading higher than the expected 0-5V (or 0-12V) reference, or the coil is failing to pull the line low when the PCM commands a charge event, or the PCM's current-sense feedback never sees the expected 5-15A primary current ramp during the 2-6 ms dwell window.
Cheapest-first ladder
- Visually inspect the coil A connector for backed-out pins, green corrosion, or a chafed wire shorted to 12V — a wire pinched against a bracket and rubbed through to a 12V source is a classic P2301 cause.
- Ohm the primary winding pin-to-pin — spec is 0.4-1.5 ohms; an open primary (OL reading) is a common cause of the PCM seeing the IGT line stuck high because there's no winding to pull current through.
- Scope the IGT trigger pulse at the coil during cranking — you should see a clean 0-5V (or 0-12V) square wave with 2-6 ms dwell; if you see the trigger pulse but the line never collapses to ground, the coil's internal driver transistor is failed open.
- On platforms where the PCM uses an external ignition module instead of internal coil drivers, ohm the module's ground reference and check for the expected current-feedback signal. Expensive-misdiagnosis caveat: swap coil A with the coil from an adjacent cylinder and clear the code — if P2301 follows the coil to the new cylinder, it's the coil; if it stays on the original cylinder, it's the harness, the connector, or the PCM driver itself. A $40 coil swap-test saves the $80 misdiagnosis fee.
Vehicle-specific patterns2001-2007 GM LSx V8 (LS1/LS2/LS6 in Camaro SS, Corvette, GTO, Silverado SS) sees P2301 most often from the OEM coil-pack pigtails where the insulatio…
- 2001-2007GM LSx V8 (LS1/LS2/LS6 in Camaro SS, Corvette, GTO, Silverado SS) sees P2301 most often from the OEM coil-pack pigtails where the insulation hardens and cracks against the valve-cover mounting bracket — repair the pigtail rather than replacing the harness.
- 2004-2010Ford 4.6L/5.4L 3V Triton COP coils throw P2301 when the long extension boot allows secondary spark to track back up to the primary terminals and damage the internal driver — replace the boot at every plug service to prevent it.
- 2011+Ford 5.0 Coyote uses a coil-pack design that's more reliable than the Triton COPs but throws P2301 from melted connectors when underhood temps run high.
- 2007-2018Toyota 2GR-FE / 2AZ-FE rarely throws P2301 before 100K miles; when it does, the failure is typically the coil itself rather than the harness. Mercedes-Benz M271 (1.8L supercharged 4-cyl, 2003-2012 C-Class/E-Class) and M273 (5.5L V8, 2007-2014 E-Class/S-Class/CLS) sees coil primary failures clustering at 80-120K miles — the M273 in particular has had multiple TSBs around coil-pack heat shielding. Common pattern: ignition coil A usually = cylinder 1 on most Ford/GM/Toyota platforms but can vary — verify against the OEM wiring diagram before swap-testing.
Estimated repair$40 (single coil DIY) to $400 (full set + labor on a V8).
Look up another code
P2301 — frequently asked
What does a P2301 code mean?
Secondary (high-voltage) side fault on cylinder 1 coil.
What causes a P2301 code?
Common causes: Failed coil; Bad plug wire/boot; Worn spark plug.
What are the symptoms of a P2301 code?
Typical symptoms: Misfire on cyl 1; Check engine light; Rough running.
Is it safe to drive with a P2301 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $50-$400.
How do I diagnose a P2301 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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