P0231 on Subaru: How to Diagnose & Fix
Fuel Pump Secondary Circuit - Low
2 Subaru models · 2 documented issues · 2 critical
P0231 on Subaru by model: symptoms, diagnosis and fix
Certain 2019-2020 Ascents are covered by low-pressure fuel pump recalls (Subaru WRD-20 / NHTSA 20V-218 for 2019 models, expanded by WRG-21 / NHTSA 21V-587 to 2019-2020 models). The pump impeller was made with a lower-density material that can absorb excessive fuel and deform until it interferes with the pump body. A deformed impeller reduces fuel delivery, causing engine stalling, rough running, or inability to start. This is a safety concern as stalling can occur without warning during driving. The recall was coordinated across multiple manufacturers using the same Denso fuel pump.
Common Symptoms
- Engine stalling without warning while driving
- Rough idle or engine misfires
- Extended cranking before engine starts
- Loss of power during acceleration
- Check engine light with fuel system codes
- Vehicle fails to start
How to Fix
Check recall status by VIN at subaru.com/owners/recalls or NHTSA.gov. Recalls WRD-20 (NHTSA 20V-218) and WRG-21 (NHTSA 21V-587) provide free low-pressure fuel pump replacement at any Subaru dealer. The updated pump uses a revised impeller material resistant to fuel component absorption. If you experience stalling before recall repair, avoid situations where a stall could be dangerous.
Sources for this issue (6)
- NHTSA Recall 20V-218 Part 573 Safety Recall Reportrecall
- NHTSA Recall 21V-587 Part 573 Safety Recall Reportrecall
- Fuel pump recall - Subaru Ascent Forumforum
- Subaru Denso Fuel Pump Lawsuit - Seeger Weissmedia
- Subaru Outback Ascent Impreza Legacy Recalled Defective Fuel Pump - Torque Newsmedia
- Subaru Recalls Nearly All Carlines Fuel Pump Failure - Torque Newsmedia
2019 Crosstreks (along with various 2013-2020 Subarus) were built with Denso low-pressure in-tank fuel pumps whose plastic impeller absorbs fuel and swells. The swollen impeller binds against the pump body, causing rough running, no-start, and unexpected engine stalls at highway speed. The Crosstrek was not included in Subaru's fuel pump recalls (WRD-20 covered 2019 Impreza, Outback, Legacy and Ascent), but 2017-2020 Crosstreks are in the Cohen v. Subaru of America class settlement (D.N.J.), which provides an extended fuel pump warranty and reimbursement for past fuel pump repairs.
Common Symptoms
- engine stall without warning
- long crank or no-start when hot
- rough running
- check engine light with fuel pressure codes
How to Fix
The Crosstrek has no fuel pump recall, so a VIN recall check will not show one. If the engine stalls, long-cranks or runs rough, have the dealer check fuel pressure and inspect the low-pressure pump, and ask whether the repair is covered by the extended fuel pump warranty (15 years from pump replacement or 150,000 miles) from the Cohen v. Subaru of America class settlement, which includes 2017-2020 Crosstreks. Keep repair invoices for any reimbursement claim.
Call to confirm they can assess your vehicle and perform the stated work. Search results do not confirm qualification, eligibility or coverage.
Sources for this issue (3)
P0231 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 P0231 mean on a Subaru?
P0231 stands for "Fuel Pump Secondary Circuit - Low." This code indicates the engine computer detected a low-voltage condition in the fuel pump's secondary (driver/output) control circuit. Many vehicles control the fuel pump through a relay or a dedicated driver module, and the computer monitors the voltage on that circuit to confirm the pump is being powered correctly. When the feedback voltage stays lower than expected, P0231 sets. Because the fuel pump supplies pressurized fuel to the injectors, this fault can cause hard starting, stalling, or no-start conditions. On Subaru it is documented across 2 models: Ascent, Crosstrek.
What are the most common causes of P0231?
The most common causes of P0231 are: Faulty fuel pump relay, Corroded or loose connector at the pump or relay, Damaged or shorted wiring in the pump power circuit, Poor ground for the fuel pump circuit, Failing fuel pump drawing abnormal current, Faulty fuel pump driver module, PCM/ECM internal driver fault (rare). The specific cause varies by vehicle.
How much does it cost to fix P0231 on a Subaru?
Repair costs vary widely with the root cause and Subaru model; each issue on this page carries its own estimate where one is published.
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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.