Injector Circuit / Open — Cylinder 4
The DURAMAX-P0204 (Duramax) diesel fault code means: Injector Circuit / Open — Cylinder 4. This is a serious severity code.
- Keep driving?
- Yes, with caution
- DIY difficulty
- intermediate
- Estimated cost
- $400-$900 per injector (LB7 often needs all 8 done; $3,000-$5,500 total)
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View pilot availability →What Are the Symptoms of DURAMAX-P0204?
- Rough idle or misfire at idle
- White or black smoke from exhaust
- Reduced power / limp mode
- Hard starting or long cranking
- Check Engine Light illuminated
What Causes DURAMAX-P0204? (Most Likely First)
- Failed injector solenoid on cylinder 4 (LB7 notorious for this) Very Likely
- Open or damaged injector harness wiring to cylinder 4 Likely
- Corroded valve cover pass-through connector (LB7 under-valve-cover harness) Likely
- FICM or injector driver module fault Possible
Can I Still Drive with DURAMAX-P0204?
Yes, with caution. DURAMAX-P0204 is rated serious severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
What is P0204 on a Duramax?
Duramax code P0204 (Injector Circuit Open — Cylinder 4) is a serious-severity diagnostic trouble code triggered by the engine control module when it detects a problem in the associated system. On LB7 Duramax engines (2001-2004) this code is almost always caused by cracked injector solenoid balls — a GM service campaign covered some of them but not all.
Is a Duramax P0204 safe to drive?
Yes, briefly. You can drive short distances at low load to reach a shop, but extended operation with a dead cylinder can wash down the cylinder wall with diesel fuel, diluting the oil and damaging bearings.
How much does it cost to fix P0204 on a Duramax?
Individual injector replacement runs $400-$900 parts and labor. On LB7 engines, dealers and indies almost always recommend replacing all 8 injectors at once, bringing the bill to $3,000-$5,500. The job requires removing the valve covers and the injector hold-downs.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose DURAMAX-P0204?
Scan for balance rates on all 8 cylinders; cylinder 4 balance outside ±4 mm³ confirms injector issue
Remove valve cover and inspect under-valve-cover harness for fuel saturation (classic LB7 failure)
Measure injector solenoid resistance at ECM side — should be ~0.5-2.0 ohms. Open indicates injector or harness fault
Back-probe the injector connector at the valve cover pass-through and repeat test to isolate harness vs. injector
Replace faulty injector and re-learn balance rates with Tech 2 or equivalent scan tool
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines P0204 as a generic OBD-II code)
P0204 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown:
Which Vehicles Commonly Get DURAMAX-P0204?
- 2001-2004 Chevy Silverado 2500/3500 HD 6.6L Duramax LB7
- 2001-2004 GMC Sierra 2500/3500 HD 6.6L Duramax LB7
- 2004.5-2005 Chevy Silverado 2500/3500 HD 6.6L Duramax LLY
- 2004.5-2005 GMC Sierra 2500/3500 HD 6.6L Duramax LLY
- 2006-2007 Chevy Silverado 2500/3500 HD 6.6L Duramax LBZ
- 2006-2007 GMC Sierra 2500/3500 HD 6.6L Duramax LBZ
- 2007.5-2010 Chevy Silverado 2500/3500 HD 6.6L Duramax LMM
- 2007.5-2010 GMC Sierra 2500/3500 HD 6.6L Duramax LMM
- 2011-2016 Chevy Silverado 2500/3500 HD 6.6L Duramax LML
- 2011-2016 GMC Sierra 2500/3500 HD 6.6L Duramax LML
- 2017+ Chevy Silverado 2500/3500 HD 6.6L Duramax L5P
- 2017+ GMC Sierra 2500/3500 HD 6.6L Duramax L5P
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