What is the error code for a bad fuel pump?
There isn't a single universal error code for a bad fuel pump; the most common generic codes are P0620 (Fuel Pump Control Circuit Malfunction) and P0690 (Fuel Pump Driver Module Fault), though many brands use manufacturer-specific codes.
Understanding fuel-pump related codes
In modern vehicles, the on-board diagnostics (OBD-II) system reports trouble codes when it detects a fault in the fuel delivery system or its control circuits. While P0620 and P0690 are among the codes most often associated with fuel pump or fuel-pump-control problems, the exact code can vary by make, model, and even model year. Some vehicles may trigger manufacturer-specific codes that point to the pump, the driver module, or the related wiring rather than a single universal code.
Before you jump to conclusions about a failing pump, it’s important to understand how these codes guide diagnostics. P0620 typically flags an issue in the fuel pump control circuit, while P0690 commonly points to a problem with the fuel pump driver module. Diagnosis often requires confirming electrical integrity, fuel pressure, and system wiring in addition to interpreting the code.
Beyond the code itself, technicians use additional tests—such as fuel pressure measurement, circuit checks, and component inspections—to determine whether the pump, the driver module, or another part of the fuel-delivery system is at fault.
Common diagnostic trouble codes associated with fuel-pump problems
Below are the codes most frequently cited in relation to fuel-pump issues. The list reflects common generic codes but may vary by vehicle.
- P0620 — Fuel Pump Control Circuit Malfunction
- P0690 — Fuel Pump Driver Module Fault
Where applicable, an additional note: some makes use manufacturer-specific codes that describe similar issues in the fuel-delivery pathway, so a code alone may not definitively confirm a bad pump without corroborating tests.
Signs of a failing fuel pump and how it’s tested
Code data is only part of the story. Many drivers notice physical symptoms that point toward fuel-delivery problems, which are then confirmed with pressure tests and electrical checks.
- Long crank times or the engine not starting at all
- Whining, buzzing, or other unusual noises from the fuel pump area (often audible near the rear of the vehicle)
- Loss of power or hesitation when accelerating, particularly as fuel level drops
- Inconsistent fuel pressure readings when tested with a fuel-pressure gauge
Testing often begins with verifying power to the pump and the integrity of related fuses and relays, followed by a live fuel-pressure test and inspection of the wiring to the pump and fuel-pump driver module. Only after these checks can a replacement pump or driver module be confidently recommended.
What to do if you suspect a bad fuel pump
If you see a fuel-pump related code or notice the symptoms described above, follow these steps to approach the repair safely and effectively.
- Check all related fuses and relays to ensure the pump circuit is getting power
- Inspect wiring and connections at the fuel pump, pump relay, and pump-driver module for corrosion or loose pins
- Perform a live fuel-pressure test and compare results to the manufacturer’s specification
- Review the vehicle’s service information for manufacturer-specific diagnostic procedures
- Consult a professional mechanic if the tests indicate a pump or driver module failure
Because a failing fuel pump can leave you stranded, it's important to confirm the root cause with proper testing rather than relying on a code alone.
Summary
In short, there isn’t a single universal error code for a bad fuel pump. P0620 and P0690 are two of the most commonly referenced generic codes, but many vehicles rely on manufacturer-specific codes. Accurate diagnosis combines code interpretation with fuel-pressure testing and electrical checks to determine whether the pump, the driver/module, or another component is at fault. If you experience symptoms of fuel-delivery trouble or see a related code, a structured diagnostic approach with professional inspection is the recommended path.
What code would a bad fuel pump cause?
A "bad fuel pump code" isn't a single code; it points to issues like low fuel pressure (e.g., P0087), a general circuit problem (e.g., P0230, P0627), or low flow/performance (e.g., P2635). These codes indicate problems with the fuel pump, its electrical circuit, or fuel delivery, and can cause symptoms such as stalling, a "crank but no start" condition, or loss of power. To diagnose, you can check codes with an OBD-II scanner and perform further tests like checking the fuel pump fuse and relay.
Common bad fuel pump codes
- P0087: Fuel rail/system pressure is too low. This often occurs on vehicles with common rail systems and is a sign the pump isn't supplying enough pressure.
- P0627: Fuel pump "A" control circuit is open or defective. This can be caused by a bad pump, relay, or wiring issues.
- P2635: Fuel pump "A" low flow or performance. The engine control module (ECM) detects the pump is not performing as expected.
- P0230: Fuel pump primary circuit. This indicates a problem with the main circuit that controls the fuel pump.
- P0171: System too lean. The engine has too much air and not enough fuel, which can be a symptom of a weak fuel pump.
- P0087: Fuel rail/system pressure is too low. This often occurs on vehicles with common rail systems and is a sign the pump isn't supplying enough pressure.
- P069E: Fuel pump control module requested MIL illumination. A fault was detected by the fuel pump control module.
Symptoms of a bad fuel pump
- Check engine light is on
- Difficulty starting or a "crank but no start" situation
- Longer cranking time before the engine starts
- Stalling, especially while driving
- Loss of power when accelerating
- Engine misfires
What to do
- Read the codes: Use an OBD-II scanner to get the specific diagnostic trouble code (DTC).
- Check basics: Before assuming the pump is bad, inspect the fuel pump fuse and relay. A faulty relay or a blown fuse can cause the same symptoms.
- Test fuel pressure: Use a fuel pressure gauge to measure the pressure to see if it's within the manufacturer's specifications.
- Inspect wiring: Check the fuel pump's wiring harness for any signs of damage, corrosion, or loose connections.
- Seek professional help: If you are not comfortable performing these tests, take your vehicle to a qualified mechanic for diagnosis and repair.
Can a fuel pump cause a P0171 code?
Weak Fuel Pump
As a fuel pump ages, the motor's components can wear, making it less efficient. If the pump is unable to feed the system with enough fuel, it can trigger the P0171 code and the CEL. A quick test of the fuel pump's power helps rule out this common cause.
What is the OBD code for a fuel pump?
Common causes for the P069E code include a faulty fuel pump, bad pressure sensors, or problems with the fuel pressure relays. The symptoms that accompany the P069E code include an illuminated check engine light, hard or no-start conditions, and engine performance problems.
Is the P0230 code serious?
Driving with the P0230 trouble code is not advised. If this code appears when you use your OBD-II scan tool, you should bring your vehicle to a repair shop for diagnosis and repair immediately.
