Injector Circuit / Open — Cylinder 1
The DURAMAX-P0201 (Duramax) diesel fault code means: Injector Circuit / Open — Cylinder 1. This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- intermediate
- Estimated cost
- $400-$900 per injector (LB7 often needs all 8 done; $3,000-$5,500 total)
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Common Symptoms
- 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
Probable Causes (Ranked by Likelihood)
- Failed injector solenoid on cylinder 1 (LB7 notorious for this) Very Likely
- Open or damaged injector harness wiring to cylinder 1 Likely
- Corroded valve cover pass-through connector (LB7 under-valve-cover harness) Likely
- FICM or injector driver module fault Possible
Step-by-Step Diagnostic Procedure
Scan for balance rates on all 8 cylinders; cylinder 1 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
Common Fixes by Vehicle
What techs usually find when diagnosing DURAMAX-P0201 on specific platforms — tap a platform for the fix and the exact part:
2001-2004 GMC/Chevy 2500/3500 6.6L LB7 Duramax Advanced DIY
P0201 (injector 1 circuit) on the LB7 is the infamous LB7 injector problem -- cup seals fail internally, causing fuel to leak into the coolant or cylinders. GM extended the LB7 injector warranty to 200K miles but most are now out of coverage. Replacement is a valve-cover-off job requiring 8 injectors + install kit; $3,500-$5,500 at a shop. The job is DIY-able over a weekend with a shop manual and takes 12-16 hours.
Labor: 12-16 hoursFrequently Asked Questions
What is P0201 on a Duramax?
Duramax code P0201 (Injector Circuit Open — Cylinder 1) 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 P0201 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 P0201 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.
P0201 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown: