P0090 — Fuel Metering Solenoid – Open Circuit #

Note: The description of code P0090 may vary depending on the vehicle manufacturer.

• Fuel Metering Control Circuit/Open (GM, Ford)
• Fuel Pressure Regulator 1 Control Circuit/Open (Volkswagen, Audi, Mercedes-Benz)
• Fuel Metering Valve Solenoid Control Circuit/Open (Toyota, Honda, Nissan)
• Fuel Volume Regulator Control Circuit/Open (Mazda, Subaru, Hyundai)

Summary of DTC P0090 #

The P0090 diagnostic trouble code (DTC) indicates an open circuit detected in the fuel metering solenoid control circuit. This solenoid, sometimes called the fuel pressure regulator valve or fuel metering valve, is an electronic device that adjusts the amount and pressure of fuel delivered to the engine. The Powertrain Control Module (PCM), which is the vehicle’s main engine computer, monitors this circuit to ensure it is functioning correctly. When the PCM senses that the circuit is open—meaning there is a break or high resistance—it triggers code P0090. This issue can lead to various drivability concerns, from hard starting to engine stalling, and may affect fuel efficiency and emissions. Prompt diagnosis and repair are recommended to avoid further complications.

Common Symptoms for DTC P0090 #

When P0090 appears, you’ll likely notice several performance issues. The symptoms can vary depending on the severity of the open circuit and the specific vehicle, but most drivers or technicians will encounter one or more of the following:

• Check Engine Light illuminated
• Hard starting, especially when the engine is warm
• Engine stalling or hesitation under acceleration
• Decreased engine power or “limp mode” activation
• Poor fuel economy
• Rough or uneven idle
• Strong fuel odor (rare but possible)

Most Likely Causes for DTC P0090 #

The P0090 code is typically triggered by electrical faults within the fuel metering solenoid circuit. Understanding the most common causes can save you valuable diagnostic time. Here they are, ranked by how often they’re found:

1. Damaged, broken, or corroded wiring/connectors to the fuel metering solenoid
2. Faulty fuel metering solenoid (internal open circuit)
3. Failed or shorted PCM driver circuit (internal PCM fault)
4. Poor ground connection for fuel system electronics
5. Blown fuse or faulty relay in the fuel solenoid circuit

Step-by-Step Diagnosis for DTC P0090 #

Proper diagnosis is key to resolving P0090 efficiently and preventing repeat failures. Follow these steps in order, and always refer to your OEM (Original Equipment Manufacturer) service information for vehicle-specific instructions:

1. Verify the code: Use an OBD-II scanner to confirm P0090 is present and check for any related codes.
2. Visual inspection: Inspect the fuel metering solenoid wiring and connector for damage, corrosion, or loose pins.
3. Check circuit continuity: Using a digital multimeter, test for continuity and resistance in the solenoid control circuit between the PCM and the solenoid connector.
4. Test the solenoid: Disconnect the solenoid and measure its resistance. Compare to OEM specs; infinite resistance indicates an open circuit inside the solenoid.
5. Inspect fuses and relays: Locate and test any fuses or relays related to the fuel metering solenoid circuit.
6. Test PCM output: If the circuit and solenoid are good, check for proper control signal from the PCM at the solenoid connector (following OEM guidelines).
7. Clear the codes and retest: After repairs, clear the code and road test to confirm the issue is resolved.

Possible Repairs for DTC P0090 #

Once you’ve pinpointed the root cause, apply the appropriate fix. Here are the most common repairs linked to each typical cause:

• Repair or replace damaged wiring/connectors: Fix any broken, corroded, or shorted wires and clean electrical contacts.
• Replace the fuel metering solenoid: Install a new OEM solenoid if the original is internally open or out of spec.
• Repair or replace PCM: If the PCM driver circuit is faulty, repair or replace the PCM as per manufacturer instructions.
• Restore ground or power supply: Clean and secure ground connections; replace blown fuses or faulty relays.

Can You Drive with Code P0090? #

Driving with P0090 is not recommended. While some vehicles may still operate, you risk sudden loss of power, engine stalling, or unpredictable fuel delivery that could leave you stranded or damage the engine. Additionally, poor fuel metering can increase emissions and may cause the vehicle to enter “limp mode,” limiting your speed and performance. Address the issue as soon as possible for your safety and to prevent further component damage.

Vehicles Most Commonly Affected by DTC P0090 #

Although P0090 is a generic OBD-II code and can appear on any modern gasoline or diesel vehicle, it’s most frequently observed on models with electronically controlled high-pressure fuel systems. Here are some examples:

• GM vehicles (Chevrolet, GMC, Cadillac, Buick, Opel, Vauxhall)
• Ford vehicles (including some Mazda models)
• Volkswagen and Audi (TDI diesel engines)
• Mercedes-Benz (CDI diesel engines)
• Toyota, Honda, and Nissan diesel applications
• Mazda, Subaru, Hyundai (especially diesels)

Common Mistakes & Best Practices for P0090 #

Mistakes during diagnosis or repair can waste time and money. Keep these tips in mind to avoid common pitfalls:

• Don’t replace the fuel metering solenoid before confirming wiring integrity
• Avoid clearing the code without fixing the root cause
• Use OEM wiring diagrams for accurate pinout and circuit tracing
• Test both power and ground at the solenoid connector
• Always verify repair by clearing codes and retesting under real driving conditions

Express FAQ for DTC P0090 #

Got quick questions? Here are some fast answers to the most common concerns:

• Q: Can a bad fuel metering solenoid cause hard starting or stalling?
  A: Yes, an open circuit or failed solenoid can disrupt fuel delivery, leading to hard starts, stalling, or rough running.
• Q: Will P0090 always trigger a check engine light?
  A: In most cases, yes. However, some vehicles may store the code as “pending” before illuminating the light after several drive cycles.
• Q: Is it safe to try and bypass the solenoid to “get home”?
  A: No. Bypassing the solenoid can cause serious engine damage or create a fire hazard. Always address the fault properly.