Ignition Coil G Primary Control Circuit Low
The P2312 code means the vehicle's onboard diagnostic system has detected: Ignition Coil G Primary Control Circuit Low. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $50 - $350 (parts and labor)
Best-selling code reader on Amazon. Reads and clears check engine codes on any 1996+ vehicle. Under $30.
Check Price on AmazonAffiliate link -- we earn a commission at no extra cost to you.
Essential for diagnosing sensor codes, checking voltage, and testing circuits. Under $15 and pays for itself on the first job.
Check Price on AmazonAffiliate link -- we earn a commission at no extra cost to you.
Common Symptoms
- Engine misfire on cylinder 7
- Check Engine Light flashing
- Noticeable engine roughness
- Reduced power output
- Raw fuel smell from exhaust
Probable Causes (Ranked by Likelihood)
- Failed ignition coil G Very High
- Damaged wiring to coil G High
- Corroded coil G connector Moderate
- Fouled spark plug on cylinder 7 Moderate
Step-by-Step Diagnostic Procedure
-
Swap coil G with another cylinder coil to confirm the fault
-
Inspect and replace the spark plug on cylinder 7
-
Check coil G connector for corrosion
-
Measure coil G primary resistance
-
Inspect the wiring harness for heat damage from exhaust
Frequently Asked Questions
Can I drive with code P2312?
Short distances only. A misfire on one cylinder of a V8 may feel less severe but still damages the catalytic converter over time.
What causes P2312?
A failed ignition coil on cylinder 7. On V8 engines, consider replacing all 8 coils as preventive maintenance if mileage is above 100,000.
Is P2312 expensive to fix?
Typically $50 to $350. V8 ignition coils are inexpensive. Replacing all 8 as a set is cost-effective and prevents future failures.
Sources
This page is built from documented references. Verify against your own service info before repair work.
Explore More
Was this helpful?
Send this to whoever is fixing the car — your mechanic, or the person asking what the light means.