P203F on Cadillac: How to Diagnose & Fix
Reductant Level Too Low
1 Cadillac model · 1 documented issue · 1 critical · $600-$1,500 repair
P203F on Cadillac by model: symptoms, diagnosis and fix
The fuel pump power control module (FPCM), mounted under the vehicle near the fuel tank on 9-speed 2.0T LSY XT4s, fails internally and stops commanding the in-tank pump. The failure is typically abrupt with no preceding driveability symptoms: the engine cuts out at speed or refuses to restart after a normal shutdown, and the vehicle cranks but will not fire. Owners report repeat failures on the same vehicle. GM opened a fuel pump control module recall (campaign N252516900) covering a subset of build ranges, but NHTSA complaints show owners with out-of-scope VINs experiencing identical failures, and the pattern spans 2021 through 2025 build years.
Common Symptoms
- Engine suddenly shuts off while driving
- Cranks but will not start
- Complete loss of motive power with no warning lights
- Vehicle stalls at idle or at a stoplight and must be towed
- Repeat failure after previous fuel pump repair
How to Fix
Diagnose with a scan tool for P203F (fuel pump control module performance) and related low fuel-rail-pressure codes; confirm no pump command / no pump power with the module commanded on. The repair is replacement of the fuel pump power control module (and in some cases the in-tank pump module assembly), followed by programming. Check the vehicle's VIN against GM recall N252516900 first, as covered vehicles get the module replaced at no charge. Because failure is sudden and total, do not defer the repair once the code has been stored.
Sources for this issue (3)
P203F 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 P203F mean on a Cadillac?
P203F stands for "Reductant Level Too Low." Set when the PCM determines the reductant (DEF/AdBlue) level in the tank is too low for the SCR system to properly reduce NOx. This is typically a genuine low-DEF condition requiring a refill, though a stuck-low level sensor can also trigger it. On modern diesels, ignoring it leads to escalating speed derate and eventual no-restart inducement. On Cadillac it is documented across 1 model: XT4.
What are the most common causes of P203F?
The most common causes of P203F are: Genuinely low DEF/AdBlue level (needs refill), Faulty reductant level sensor reading low, DEF leak from the tank/lines, Contaminated or crystallized DEF affecting sensing, PCM/dosing control module fault. The specific cause varies by vehicle.
How much does it cost to fix P203F on a Cadillac?
Published repair estimates on Cadillac range from $600 to $1,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P203F on a different make?
View P203F across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.