OBD-II Code
P2309
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$40–$320
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
$40 (single coil DIY) to $320 (full set on a V8).
P2309 means the PCM detected a low-voltage condition on the primary control circuit of ignition coil D — the IGT command line to coil D is reading lower than the expected 0-5V (or 0-12V) reference, or the primary current the PCM monitors is below the 5-15A peak it expects to see during the 2-6 ms dwell window.
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 follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
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
- Check engine light
Read the full diagnostic procedureP2309 means the PCM detected a low-voltage condition on the primary control circuit of ignition coil D — the IGT command line to coil D is reading lo…
P2309 means the PCM detected a low-voltage condition on the primary control circuit of ignition coil D — the IGT command line to coil D is reading lower than the expected 0-5V (or 0-12V) reference, or the primary current the PCM monitors is below the 5-15A peak it expects to see during the 2-6 ms dwell window.
Cheapest-first ladder
- Inspect the coil D connector and pigtail for green corrosion, backed-out pins, and chafed-through insulation against brackets, valve-cover bolts, or the intake manifold — connector and harness faults are the #1 cause of low-side primary codes and cost nothing to find with a flashlight and a pick.
- Ohm the primary winding pin-to-pin — 0.4-1.5 ohms typical; 0.0 ohms indicates shorted primary, OL indicates open, both condemn the coil.
- Scope the IGT trigger pulse with a low-voltage scope — expect a clean 0-5V (or 0-12V) square wave with 2-6 ms dwell; missing pulse traces back to the PCM driver or the harness between PCM and coil.
- Verify 12V feed at the coil with key-on — battery voltage expected; low or absent feed traces back to the ignition relay or fusible link. Expensive-misdiagnosis caveat: swap coil D with an adjacent coil and clear the code — if P2309 follows the coil to the new cylinder, it's the coil; if it stays on the original cylinder, it's the harness, connector, or PCM driver. A $40 coil swap-test saves the $80 misdiagnosis fee.
Vehicle-specific patterns2005-2014 GM LSx V8 (LS1/LS2/LS3 in Silverado/Camaro/Corvette) sees coil D primary codes from the same valve-cover-mounted heat-soak failures as coil…
- 2005-2014GM LSx V8 (LS1/LS2/LS3 in Silverado/Camaro/Corvette) sees coil D primary codes from the same valve-cover-mounted heat-soak failures as coils A/B/C — the driver-side bank coils (cylinders 1/3/5/7 in LS firing order) typically fail first because of exhaust crossover proximity.
- 2004-2010Ford 4.6L/5.4L 3V Triton sees P2309 from melted/water-intruded COP connectors that plague all per-cylinder primary codes on this platform.
- 2011+Ford 5.0 Coyote (Mustang GT, F-150) sees primary low-side codes from harness chafe over the intake manifold and from connector heat damage near the cylinder head.
- 2007-2018Toyota 2GR-FE 3.5L V6 (Camry, Highlander, Sienna, RAV4) and 2AZ-FE 2.4L typically run 100-150K miles before throwing primary-circuit codes; failures are usually a single coil rather than a set. Mercedes M271 (1.8L supercharged 4-cyl, 2003-2012 C-Class/E-Class) and M273 (5.5L V8, 2007-2014 E-Class/S-Class/CLS) coil primary failures cluster at 80-120K miles, with multiple TSBs around coil-pack heat shielding on the M273. Mazda RX-8 Renesis rotary trailing/leading coil failures appear earlier (50-70K miles) from rotary firing frequency. Common pattern: coil D usually maps to cylinder 4, 6, or whatever the OEM firing-order map assigns — never assume cylinder number from coil letter; verify against the OEM wiring diagram before swap-testing.
Estimated repair$40 (single coil DIY) to $320 (full set on a V8).
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