P2931 – Fuel Pump Secondary Circuit Range/Performance

System: Powertrain | Standard: ISO/SAE Controlled | Fault type: Range/Performance

Definition source: SAE J2012/J2012DA (industry standard)

DTC P2931 indicates a problem classified as a range/performance fault in the fuel pump secondary circuit. In practical terms, a control module has determined that what it is commanding or expecting in the secondary-side fuel pump electrical path does not align with what it is seeing or how the circuit is responding over time. This is not the same as a simple open, short-to-ground, or short-to-power; it is a plausibility/response issue that must be confirmed with testing. The exact monitor strategy, the components considered part of the “secondary circuit,” and the enable criteria vary by vehicle, so always verify wiring diagrams, connector views, and pinpoint tests in the correct service information before repairs.

What Does P2931 Mean?

P2931 – Fuel Pump Secondary Circuit Range/Performance means the powertrain control system has detected that the fuel pump secondary circuit is operating outside its expected range or is not performing as expected. As defined by SAE DTC conventions, “range/performance” points to a plausibility concern: the circuit feedback, inferred load behavior, or response to a command does not match what the module considers valid under the current operating conditions. The code identifies the affected function (fuel pump secondary circuit) and the fault type (range/performance), but it does not, by itself, prove a specific failed part or confirm fuel delivery problems without follow-up diagnosis.

Quick Reference

  • Subsystem: Fuel pump secondary circuit (the commanded/controlled electrical path and any associated monitoring or feedback used to validate operation).
  • Common triggers: Commanded pump activity that does not produce the expected electrical response; implausible feedback; slow or inconsistent circuit response during key-on prime or running conditions.
  • Likely root-cause buckets: Wiring/connector issues, power/ground integrity problems, fuel pump driver/control device concerns (varies by vehicle), fuel pump electrical load issues, module/software or calibration edge cases.
  • Severity: Varies; may be intermittent with minimal symptoms, or may cause reduced performance, stalling, or a no-start if the system cannot maintain fuel delivery.
  • First checks: Verify battery/charging health, scan for related fuel/power supply DTCs, review freeze-frame, inspect connectors and grounds, and confirm the pump can be commanded and shows stable feedback in live data (if available).
  • Common mistakes: Replacing the fuel pump immediately without confirming circuit integrity, ignoring voltage-drop/ground testing, and overlooking intermittent connector tension or corrosion that only appears under load.

Theory of Operation

The fuel pump is typically powered and controlled through a dedicated circuit that may include a relay, fuse(s), a control driver module or integrated driver stage, and the pump itself. “Secondary circuit” commonly refers to the load side of the control path feeding the pump (downstream of primary control elements), though exact definitions vary by vehicle architecture. The control module may prime the pump at key-on and then adjust operation based on engine demands.

To validate performance, the module monitors circuit behavior using available signals such as command state, inferred current/load behavior, or a feedback circuit that confirms the pump circuit’s response. A range/performance fault sets when the observed behavior is plausible for neither the commanded state nor the expected response timing, even if the circuit is not fully open or shorted. Intermittent resistance changes, weak power/ground, or abnormal load characteristics can all cause this mismatch.

Symptoms

  • Warning light: Check engine light illuminated, sometimes after a key cycle or specific driving conditions.
  • Hard start: Extended cranking time, especially after sitting, if pump operation is inconsistent.
  • Stall: Engine may stall at idle or during transitions if fuel delivery becomes unstable.
  • No-start: Intermittent or persistent no-start if the pump circuit cannot respond correctly to commands.
  • Hesitation: Momentary stumble or lack of power under load when fuel supply is not maintained.
  • Intermittent behavior: Symptoms may come and go with temperature, vibration, or harness movement.
  • Reduced performance: Noticeable loss of power or poor acceleration if the system limits operation due to detected inconsistency.

Common Causes

  • High resistance, corrosion, or poor pin fit in the fuel pump secondary circuit connectors (at the pump module, in-line connector, or control module)
  • Wiring damage in the secondary circuit (chafed insulation, partial open, intermittent contact) causing the commanded vs measured response to be out of range
  • Voltage drop on the fuel pump power feed or ground path (loose fasteners, contaminated ground point, overheated terminals) affecting pump performance under load
  • Fuel pump driver/control module output not tracking commanded operation (internal driver fault or degraded output stage, varies by vehicle)
  • Fuel pump assembly wear or mechanical restriction causing slow response or inadequate flow/pressure relative to command (do not confirm without testing)
  • Fuel pump control feedback/monitoring circuit issue (where equipped), such as a distorted or unstable feedback signal leading to plausibility failure
  • Fuse/relay/socket issues that do not create a hard open but create intermittent or load-sensitive loss (heat-related contact resistance)
  • Module calibration/software issue or inaccurate learned values causing the monitor to flag range/performance (verify service information and updates where applicable)

Diagnosis Steps

Tools that help include a scan tool capable of live data and bi-directional fuel pump commands (where supported), a digital multimeter, and a test light as appropriate. A wiring diagram and connector views are essential because circuit routing varies by vehicle. For deeper checks, use back-probing tools, a fused jumper lead, and equipment to log data during a road test.

  1. Confirm the code and capture context: Scan for P2931 and any companion DTCs (power supply, communication, fuel pressure-related). Record freeze-frame data and note conditions when it set (engine load, speed, temperature), since range/performance faults are often condition-dependent.
  2. Review monitor-related data PIDs: In live data, observe the commanded fuel pump control (duty/command), any available fuel pump feedback (actual duty/voltage/current, if supported), and fuel rail pressure (if available). You are looking for a mismatch, slow response, or unstable feedback relative to command rather than a simple on/off failure.
  3. Perform a visual inspection first: Inspect accessible harness routing to the pump area, underbody runs, and the control module area (if used). Look for rub-through, pinch points, previous repairs, heat damage, or signs of moisture intrusion at connectors. Repair obvious issues before deeper testing.
  4. Check fuses/relays and their load behavior: Verify the correct fuse and any relay operation for the fuel pump circuit. Focus on terminal tension and signs of overheating at the fuse/relay socket. A range/performance fault can be caused by a marginal connection that only fails under higher current demand.
  5. Command the pump and watch response: Use bi-directional controls (if available) to command different pump states. Compare command changes to the feedback signals and/or observed fuel pressure response. If the command changes but feedback/pressure response is delayed, erratic, or limited, continue with circuit and load testing.
  6. Wiggle test while logging: With the engine running (or while commanding the pump), gently manipulate the harness and connectors in sections while logging relevant PIDs. If the command/feedback relationship changes, the fault is likely intermittent wiring/connector related. Document exactly which movement causes the deviation.
  7. Voltage-drop test power and ground under load: With the pump operating under a representative load condition, perform voltage-drop testing on the pump power feed and ground path. Excessive drop indicates resistance in wiring, connectors, relay contacts, or ground points. Move the meter leads segment-by-segment to isolate where the drop occurs rather than replacing parts blindly.
  8. Check for an intermittent/partial open: If voltage drop is normal but the issue persists, perform continuity and resistance checks with the circuit de-energized, focusing on areas that flex or vibrate. Use a dynamic check where possible (monitoring continuity while flexing the harness) to catch intermittent opens that a static test can miss.
  9. Validate the control/driver output: Where the vehicle uses a fuel pump driver/control module, verify that the output and any feedback/monitoring circuits behave consistently with commanded operation. If wiring and power/ground are verified good, an output stage that cannot maintain performance under load may be suspect (confirm with service information test procedures).
  10. Correlate with fuel delivery evidence: If the electrical side checks out, confirm whether the fuel system response aligns with commands (for example, a sluggish pressure change or inability to maintain pressure under load). This helps separate an electrical range/performance issue from a mechanical/hydraulic limitation, while avoiding assumptions based on the DTC alone.
  11. Clear, verify, and complete a confirmation drive: After repairs, clear DTCs and repeat the same operating conditions captured in freeze-frame. Use live-data logging to confirm the commanded vs actual behavior remains stable. Ensure readiness/monitors complete as applicable and confirm P2931 does not return.

Professional tip: Treat P2931 as a plausibility problem between what the module commands and what it observes. The fastest path is often to log command and feedback (and fuel pressure if available) during the exact conditions that set the code, then use voltage-drop testing under load to pinpoint resistance that a simple continuity check will not reveal.

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Possible Fixes & Repair Costs

Repair costs for P2931 vary widely because the underlying issue can be anything from a simple connection problem to a component or control-side fault. Total cost depends on accurate diagnosis, the parts involved, labor time, and access to the fuel pump secondary circuit components.

  • Clean, repair, or reseat fuel pump secondary circuit connectors; restore proper terminal tension and contact integrity
  • Repair damaged wiring (opens, chafing, corrosion, pin-fit issues) in the fuel pump secondary circuit harness routing
  • Perform verified power and ground repairs (including voltage-drop proven repairs) affecting the fuel pump secondary circuit operation
  • Replace a failing fuel pump control relay or related switching component only after test confirmation (varies by vehicle design)
  • Replace the fuel pump driver/control module if tests show it cannot command or monitor the secondary circuit correctly (varies by vehicle)
  • Replace the fuel pump assembly only if circuit tests and performance checks confirm the pump cannot respond properly under commanded conditions
  • Update or reprogram the control module software if service information indicates calibration-related range/performance sensitivity and all wiring checks pass

Can I Still Drive With P2931?

Driving with P2931 may be possible if the vehicle runs normally, but it is not recommended to ignore it because a fuel pump secondary circuit range/performance issue can become intermittent and lead to loss of fuel delivery. Do not drive if you experience stalling, no-start, strong hesitation, reduced power that affects merging, or any warning indicating compromised braking/steering assist; have the vehicle diagnosed promptly.

What Happens If You Ignore P2931?

Ignoring P2931 can result in worsening intermittents, extended crank or no-start events, unexpected stalls, and repeated illumination of the malfunction indicator. Continued operation with an unresolved fuel delivery control issue may increase the chance of drivability complaints and can complicate diagnosis if additional codes set due to secondary effects.

Related Codes

  • P2930 – Fuel Pump Secondary Circuit High
  • P2929 – Fuel Pump Secondary Circuit Low
  • P2928 – Fuel Pump Secondary Circuit/Open
  • P2927 – Fuel Cutoff Valve “B” Performance
  • P2926 – Fuel Cutoff Valve “B” Control Circuit High
  • P2925 – Fuel Cutoff Valve “B” Control Circuit Low
  • P2924 – Fuel Cutoff Valve “B” Control Circuit/Open
  • P2923 – Fuel Cutoff Valve “A” Performance
  • P2922 – Fuel Cutoff Valve “A” Control Circuit High
  • P2921 – Fuel Cutoff Valve “A” Control Circuit Low

Key Takeaways

  • P2931 indicates a fuel pump secondary circuit range/performance problem, not a guaranteed fuel pump failure.
  • Range/performance faults are commonly caused by response or plausibility issues seen by the control module, often tied to wiring/connector integrity.
  • Verify the condition with service information and confirm the fault using test-driven checks (including voltage-drop testing under load).
  • Intermittent faults are common; use wiggle testing and live-data logging to capture when the monitor fails.
  • Repair only what is proven faulty to avoid repeat comebacks and unnecessary parts replacement.

Vehicles Commonly Affected by P2931

  • Vehicles using an electronically controlled fuel pump with a monitored secondary circuit
  • Vehicles equipped with a fuel pump driver/module that reports circuit performance to the powertrain controller
  • Platforms with fuel delivery strategies that modulate pump output based on operating conditions
  • Vehicles with underbody harness routing exposed to moisture, debris, or physical impact (varies by vehicle)
  • Higher-mileage vehicles where connector fretting, corrosion, or terminal tension loss is more likely
  • Vehicles that have had recent fuel system, tank, or rear-harness repairs where connector seating may be disturbed
  • Vehicles operated in conditions that accelerate corrosion at connectors and grounds (varies by environment)
  • Vehicles with prior electrical modifications that share power/ground paths with fuel delivery circuits (varies by vehicle)

FAQ

Does P2931 mean the fuel pump is bad?

No. P2931 only indicates the fuel pump secondary circuit is not performing within the expected range as judged by the control module’s monitor. The cause may be wiring/connector issues, power/ground problems, a control/driver fault, or the pump itself; testing is required to confirm.

What is the “fuel pump secondary circuit” referring to?

It refers to the monitored portion of the fuel pump electrical control path that the module uses to command and/or verify fuel pump operation. The exact architecture varies by vehicle, but it commonly involves control-side switching/driver circuitry and the associated wiring and connectors.

Can a weak battery or poor ground trigger P2931?

Yes. If system voltage quality or ground integrity is poor, the fuel pump command and feedback behavior can deviate from expected response, leading to a range/performance result. Confirm with charging-system checks and voltage-drop testing on the relevant power and ground paths.

Why is this called a range/performance code instead of circuit high/low?

Range/performance indicates the circuit’s behavior is implausible or not responding as expected, rather than a straightforward high-input or low-input electrical state. The controller is evaluating how the circuit performs over time or under command, not just a single voltage level.

What should I check first to avoid unnecessary parts replacement?

Start with connector and harness inspection at accessible points, then verify power and ground integrity with loaded voltage-drop testing, and confirm commanded versus observed behavior using live data where available. If the concern is intermittent, perform a wiggle test while logging data to capture the failure.

If P2931 is intermittent, prioritize reproducing the fault under similar operating conditions and verify wiring/connector integrity before replacing components.