P1248 — Second Fuel Pump Faulty or Ground Fault

What are the symptoms of P1248?

Drivers most often notice: loss of power under load, fuel smell in severe cases, Check Engine Light on, rough idle and hesitation.

Will P1248 clear itself?

Sometimes P1248 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What is the most common cause of P1248?

The most common causes are: faulty fuel pressure regulator, weak fuel pump or clogged fuel filter, vacuum or intake leaks skewing the mixture.

How do I diagnose P1248 myself?

Start with a scan: confirm P1248, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the second fuel pump faulty or ground, and verify the suspect component against live data before buying parts.

Is it safe to drive with P1248?

Drive with caution. Mixture and fuel-pressure faults can cause stalling, hesitation in traffic and — when severe — catalyst damage. Avoid long trips until diagnosed.

When your scan tool pulls code P1248, it means the engine computer has detected that the fuel delivery system is operating outside its intended parameters. Officially this code refers to a "Second Fuel Pump Faulty or Ground Fault" condition. The powertrain control module constantly watches how the engine feeds fuel and controls air-fuel mixture, and when those readings stay out of range long enough across successive drive cycles, P1248 gets stored and the check engine light activates. This is not an emission-only code — it falls under the broader powertrain category, meaning it can affect driveability.

The freeze frame snapshot captured alongside P1248 is worth its weight in gold during diagnosis. It records engine speed, load percentage, coolant temperature, vehicle speed, and other sensor data the exact moment the fault crossed the threshold. That snapshot tells you whether the problem showed up at idle, under hard acceleration, or at cruising speed, which immediately narrows your troubleshooting path. Without that context, you are essentially guessing based on symptoms alone.

Fuel system faults rarely appear in isolation. P1248 often shows up alongside lean-burn codes or fuel trim codes because the root problem — whether it is a weak pump, restricted filter, or faulty regulator — throws off the mixture. The engine management system compensates up to its adaptive limits, then the check engine light comes on. Addressing the underlying mechanical or electrical fault usually clears the secondary codes once the system returns to normal operation.

Symptoms of P1248

Engine power feels flat when you put your foot down, particularly under load or climbing a grade. That lack of response happens because the engine is not getting the fuel it needs to match the driver's demand. Depending on how severe the fault is, you may notice the engine stumbling or hesitating during acceleration rather than pulling smoothly.

The check engine light stays illuminated once P1248 sets. On some vehicles the light may flash briefly during a active fault, then hold steady. Either way, the lamp indicates the control module has confirmed a genuine problem and logged it in permanent memory.

Rough idle often accompanies this code. The engine may shake more than usual at standstill, and you might feel subtle misfires rippling through the steering wheel or seat. Low fuel pressure at idle creates an unstable combustion event, and the PCM cannot fully compensate for the deficiency.

Hard starting or extended cranking before the engine fires is another common complaint. When the secondary pump cannot maintain adequate pressure in the fuel rail, residual pressure bleeds off overnight. That means the engine requires several extra seconds of cranking to build sufficient flow for a cold start.

You may also notice noticeably higher fuel consumption. The PCM enriches the mixture to prevent a lean miss, but that correction comes at the cost of mileage. If your fuel economy suddenly drops without a driving habit change, a fuel delivery problem like P1248 could be the reason.

In severe cases, a raw fuel smell becomes apparent around the engine bay or from the tailpipe. This indicates the mixture is far too rich, which can happen if a pressure regulator fails wide open or a leaking injector continuously dumps fuel into the cylinder.

Common Causes of P1248

A clogged fuel filter ranks among the most frequent triggers for this code. The filter traps debris and varnish, but eventually it restricts flow enough that the pump cannot keep the rail pressurized under demand. Restricted flow shows up as low pressure under load, exactly the condition P1248 describes.

Weak or failing fuel pump produces the same result through a different mechanism. Rather than a physical blockage, the pump itself cannot generate adequate pressure, especially when the engine demands maximum flow during hard acceleration. Pumps wear out over time and often show declining performance before complete failure.

A faulty fuel pressure regulator can push the system out of specification in either direction. If the regulator leaks internally, it allows rail pressure to drop. If it sticks closed, it can create excessive pressure that also triggers a fault code. Either scenario confuses the PCM enough to set P1248.

Vacuum leaks upstream of the fuel injectors throw off the air-fuel ratio calculation. Even though the pump and regulator work correctly, unmetered air enters the intake and creates a lean condition. The PCM sees the mixture sensor reading lean and may log a fault related to fuel delivery insufficiency.

Clogged or leaking fuel injectors deliver either too little fuel or an uneven spray pattern. Partially blocked injectors reduce flow under high-demand conditions, while leaking injectors create rich-running symptoms. Both conditions fall under the broader fuel delivery umbrella that P1248 monitors.

Contaminated or incorrect fuel sometimes triggers this code indirectly. Alcohol-blended fuels or fuel contaminated with water can affect both pump operation and injector performance. The PCM detects the resulting mixture deviation and logs the fault.

Wiring or connector issues affecting the fuel pump circuit can create a ground fault condition, which is the second half of the P1248 definition. Corroded terminals, damaged insulation, or loose connectors increase resistance and cause the module to see abnormal readings even when the pump itself functions.

How to Diagnose P1248

Pull the code with a quality OBD2 scanner and record the freeze frame data before doing anything else. That freeze frame tells you the exact operating conditions — rpm, load, temperature, speed — when the fault occurred. Reproducing those conditions during your road test makes the fault reappear reliably if the problem is intermittent.

After confirming P1248 is present, check for any related diagnostic trouble codes. Lean condition codes, fuel trim codes, or pump circuit codes often accompany this fault and point toward the actual root cause. Address those codes in conjunction with P1248 rather than treating each as a separate problem.

Consult manufacturer technical service bulletins for your specific make, model, and year. Many common codes have documented factory fixes, updated calibration files, or known component issues described in TSBs. Searching by your vehicle identification number on the manufacturer or NHTSA website can reveal relevant service campaigns.

Visually inspect the fuel pump wiring harness and electrical connectors. Look for damaged insulation, broken wires, corrosion buildup, or loose terminals. A poor ground connection specifically triggers the ground fault half of P1248. Wiggle the connectors while monitoring fuel pressure or scanner data to reveal intermittent faults.

Measure fuel system pressure at the fuel rail with a gauge while the engine runs at idle and during a load test. Compare your readings to factory specifications. Low pressure at idle suggests a failing pump or restricted filter. Pressure that drops significantly under load points to a weak pump or clogged filter. Excessive pressure indicates a stuck-closed regulator.

Check short-term and long-term fuel trim values in the scanner's live data stream. Strongly positive trims indicate the PCM is compensating for a lean condition, often caused by low fuel pressure or unmetered air. Strongly negative trims suggest a rich condition from a leaking injector or failed regulator.

Repair Options for P1248

Replacing the fuel filter typically costs between $80 and $200, including parts and labor at an independent shop. This is usually the first repair to attempt since a restricted filter is the most common cause of low-pressure faults in older vehicles.

A fuel pressure regulator replacement runs $150 to $450 depending on vehicle make and whether the regulator is a stand-alone unit or integrated with the fuel pump assembly. Some vehicles require fuel rail disassembly, which adds labor time.

Cleaning or replacing fuel injectors costs $200 to $800. Professional ultrasonic cleaning of all injectors sits at the lower end, while replacing all injectors with new OEM-equivalent units pushes toward the higher figure. Individual injector replacement costs less if only one or two are faulty.

Replacing the fuel pump itself — including in-tank pump, strainer, and often the sending unit — runs $400 to $900 for parts and labor. Tank removal is required on most vehicles, which accounts for the significant labor portion of this repair.

Wiring repairs or connector replacement costs vary widely based on accessibility. Simple connector cleaning or a single wire repair may cost under $100 in labor, while extensive harness replacement can reach several hundred dollars.

How Much Does It Cost to Fix P1248?

The total repair bill for P1248 ranges from roughly $80 for a simple filter swap up to $900 for a complete fuel pump replacement. Most diagnosed cases land in the $200 to $450 range when the fault traces to a failing pressure regulator or moderately restricted fuel system.

An accurate diagnosis before purchasing parts saves significant money. The fuel filter is inexpensive and commonly fixes the issue, but replacing a fuel pump when the filter is the culprit wastes hundreds of dollars. Follow the diagnostic sequence — pressure testing before component replacement — and you will likely avoid the maximum repair scenario.

Can You Drive with P1248?

Drive with caution. Fuel delivery faults can cause the engine to stall without warning, hesitation during acceleration, or sudden power loss in traffic situations. Prolonged operation with a severe fault risks running the catalytic converter extremely rich, which can destroy the catalyst and turn a manageable repair into an expensive emission system replacement.

Limit driving to essential trips until the fault is diagnosed and repaired. Avoid heavy loads, high-speed merging, and sustained high-demand driving. Get the vehicle to a shop or complete your own diagnostic testing before any long-distance trip.

Related OBD2 Codes

• P1200: SCP HBCC Failed To Initialize
• P1201: Key Off Voltage High

• P1202: Key Off Voltage Low