P128F on 2011-2016 Chevrolet Silverado — Fuel Rail Pressure Sensors 1 and 2 Signals - Message Counter Incorrect
1 vehicles · 1 makes · $5,000-$12,000 repair
How to diagnose and fix P128F: most-reported vehicles
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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)
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P128F 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 P128F mean?
P128F stands for "Fuel Rail Pressure Sensors 1 and 2 Signals - Message Counter Incorrect." Manufacturer-specific code. It is documented on GM vehicles (Chevrolet, GMC, Cadillac) across both direct-injection gasoline and Duramax diesel applications, and it also appears on PACCAR commercial engines listed as "engine rail pressure control - incorrect." The ECM compares the reported values and message counters from the two fuel rail pressure sensors and has determined the data is not arriving correctly or the two sensors disagree. Because the ECM can no longer trust its rail pressure reading, it typically falls back to reduced power. Expect rough running, hesitation, poor fuel economy, hard starting, or stalling.
What are the most common causes of P128F?
The most common causes of P128F are: Failed or drifting fuel rail pressure sensor (sensor 1 or sensor 2), Open, shorted, or chafed wiring in the fuel rail pressure sensor circuit, Poor connection or corrosion at a rail pressure sensor connector, Low actual rail pressure from a failing high-pressure fuel pump or restricted fuel filter, ECM/PCM fault or out-of-date software calibration. The specific cause varies by vehicle.
How much does it cost to fix P128F?
Repair costs for P128F range from $5,000 to $12,000, depending on the vehicle and root cause.
Which vehicles are affected by P128F?
Au7o has documented P128F across 1 vehicle models from 1 manufacturers: Chevrolet.
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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.