P2337 serious

Ignition Coil D Secondary Circuit

The P2337 code means the vehicle's onboard diagnostic system has detected: Ignition Coil D Secondary Circuit. This is a serious severity code.

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Keep driving?
Short distances only
DIY difficulty
hard
Estimated cost
$175 - $450 (parts and labor)
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Common Symptoms

  • Check Engine Light on
  • Persistent misfire on cylinder 4
  • Rough idle that may worsen when warm
  • Reduced power and sluggish acceleration
  • Possible engine stalling at low RPM

Probable Causes (Ranked by Likelihood)

  • Internal failure of ignition coil D secondary winding Very High
  • Cracked or worn spark plug on cylinder 4 High
  • Carbon tracking on coil boot or spark plug well Moderate
  • Excessive spark plug gap Low

Step-by-Step Diagnostic Procedure

  1. Confirm P2337 with a scan tool and review misfire counters

  2. Remove and inspect spark plug on cylinder 4 for wear, fouling, or cracking

  3. Test ignition coil D secondary resistance (typically 6,000-15,000 ohms)

  4. Inspect coil boot and spark plug well for moisture, carbon tracking, or arcing marks

Frequently Asked Questions

What does P2337 mean?

P2337 means the secondary (high-voltage) circuit of ignition coil D on cylinder 4 is malfunctioning. This is the circuit that delivers spark to the plug and typically indicates a coil or plug failure.

Can I drive with P2337?

Driving short distances is possible but not recommended for long. The misfire can overheat the catalytic converter and waste fuel.

How much does it cost to fix P2337?

Expect $175 to $450. This often requires a new coil ($80-$250) and spark plug ($10-$40) plus labor ($85-$160).

Sources

This page is built from documented references. Verify against your own service info before repair work.

P2337 on Diesel, EV & Equipment

The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:

Duramax moderate Cylinder 2 Above Knock Threshold

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