P0093: How to Diagnose & Fix — Fuel System Leak Detected - Large Leak
3 vehicles · 2 makes · $300-$12,000 repair
How to diagnose and fix P0093: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Chevrolet Silverado · 2011–2016
Silverado 2500HD/3500HD trucks with the 6.6L Duramax LML use the Bosch CP4.2 high-pressure injection pump, which was designed around European diesel and is poorly lubricated by U.S. ULSD. The pump's roller/cam interface can gall and disintegrate, sending metal shavings throughout the entire fuel system. When it lets go, it contaminates injectors, rails and lines, the engine stalls (often at speed), and the repair commonly runs ~$8,000-$10,000+ because the whole fuel system must be replaced. It was the subject of a certified multi-state class action (Chapman v. GM) whose settlement received final court approval in May 2025.
Common Symptoms
- Sudden loss of power / engine stall while driving
- Hard start or no-start
- Metal shavings / debris in fuel filter
- Rough running and misfire
- Check engine light with fuel-pressure codes
- Loud knocking from the injection pump
How to Fix
On a CP4 failure the entire high-pressure fuel system must be flushed/replaced — CP4 pump, injectors, rails, lines and filters — to clear all metal contamination; reusing contaminated parts causes repeat failure. Many owners proactively install a CP4-to-CP3 conversion kit (more tolerant of U.S. diesel) or at minimum a 'disaster prevention'/CP4 bypass kit and an upgraded lift pump and water-separating filter, and run fuel additive for lubricity. The Chapman v. GM settlement (2011-2016 trucks bought in CA, FL, IL, IA, NY, PA or TX) closed to claims about six months after its May 2025 final approval, so new repairs are generally owner-paid.
Sources for this issue (2)
Chevrolet Silverado 2500HD · 2011–2016
The 2011-2016 Duramax 6.6L diesel uses a Bosch CP4.2 high-pressure fuel injection pump that is prone to catastrophic self-destruction. The CP4 has tight internal tolerances and is not designed for the lower lubricity of American diesel fuel (compared to European diesel). When the pump fails, it sends metallic debris through the entire high-pressure fuel system, contaminating the fuel rails, injectors, and fuel lines. A single CP4 failure typically destroys $8,000-$12,000 worth of fuel system components.
Common Symptoms
- Engine cranks but will not start
- Metallic debris in fuel filter
- Loss of power followed by stalling
- Hard starting that progressively worsens
- Check engine light with fuel pressure codes
- Metal shavings in fuel system
How to Fix
Prevention: The only true prevention on the LML is replacing the CP4 with a CP3 conversion kit ($2,500-$3,500 installed), which uses the more robust pump from the 2001-2010 Duramax. Repair: For a failed CP4, the entire high-pressure fuel system must be replaced or flushed: CP4 pump, all 8 injectors, both fuel rails, high-pressure lines, and the fuel tank must be cleaned. Total cost: $8,000-$12,000 at a diesel shop. LML 'disaster kits' are repair kits of replacement rails, lines, return hoses and filters used after a CP4 failure.
Sources for this issue (5)
- Common 6.6L Duramax Diesel Engine Problems - DieselHubarticle
- 6.6 Duramax LGH - DieselHubarticle
- Faulty Diesel Fuel Pump Settlement Will Cost GM $50M - GM Authorityarticle
- 2011-16 6.6L Duramax LML Bosch Disaster Kit - Industrial Injectionarticle
- S&S Diesel LML-CP3-CARB CP4 to CP3 Conversion Kit for 2011-2016 GM 6.6L Duramax LMLarticle
Genesis G70 · 2019–2023
The fuel control valve inside the high-pressure fuel pump (HPFP) can let excess fuel into the pump as its plunger gradually wears, producing an air/fuel mixture that runs too rich. This causes a reduction or loss of motive power at low speeds, rough running, and check-engine warnings — increasing crash risk. Genesis recalled certain 2019-2023 G70 vehicles with the 2.0L turbocharged engine under NHTSA campaign 24V-528 (Genesis recall 023G); owner letters mailed September 2024. Many owners also reported the symptom (hesitation/near-stall when driving off within ~30 seconds of a cold start) before the formal recall. The remedy is an ECM software update, with the HPFP also replaced if the check-engine light is already on, performed free of charge under the recall.
Common Symptoms
- Loss of power or hesitation accelerating from a stop or at low speed
- Engine wants to stall if you drive off within ~30 seconds of starting
- Rough running / engine surging
- Check engine light, sometimes with a fuel-rail-pressure code
- Long crank or hard start
How to Fix
First verify the VIN against Recall 24V-528 (023G) — the fix is free under recall. Dealers apply an updated ECM/engine-control software calibration and replace the high-pressure fuel pump if the check-engine light is already on; the remedy pump has an updated fuel-control-valve plunger design. Out of warranty/recall, the OEM HPFP is replaced; the recall lists G70 2.0T pumps 35320-2CTB0 and 35320-2CTB1. After replacement, clear codes and confirm fuel-rail pressure is within spec.
Sources for this issue (1)
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P0093 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0093 mean?
P0093 stands for "Fuel System Leak Detected - Large Leak." This code indicates the engine computer detected a large leak in the fuel system, typically a significant drop in fuel rail pressure that it cannot maintain. It is common on high-pressure direct-injection and diesel systems, where the computer watches commanded versus actual fuel pressure. A large pressure loss suggests fuel is escaping or the system cannot build pressure. This can cause hard starting, loss of power, stalling, and is a potential fire hazard if fuel is leaking externally.
What are the most common causes of P0093?
The most common causes of P0093 are: Leaking or cracked high-pressure fuel line or fitting, Faulty fuel injector (leaking or stuck open), Failed high-pressure fuel pump, Damaged or leaking fuel pressure regulator, Loose or degraded fuel system seals/O-rings, Faulty fuel rail pressure sensor, Restricted fuel supply preventing pressure buildup. The specific cause varies by vehicle.
How much does it cost to fix P0093?
Repair costs for P0093 range from $300 to $12,000, depending on the vehicle and root cause.
Which vehicles are affected by P0093?
Au7o has documented P0093 across 3 vehicle models from 2 manufacturers: Chevrolet, Genesis.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.