P0090 – Fuel Pressure Regulator Control Circuit

Meaning

P0090 indicates a problem in the fuel pressure regulator control circuit. This is usually related to the Electronic Fuel Pressure Regulator (FPR) or the wiring/connector going to it.

The ECM/PCM controls fuel pressure electronically, and if the circuit looks open, shorted, or out of expected range, it triggers P0090.

Common Causes

🎀 Faulty Fuel Pressure Regulator
🎀 Damaged wiring or loose connectors (corroded pins, broken wires)
🎀 Faulty Fuel Rail Pressure Sensor (in some systems)
🎀 Bad ECM/PCM (rare)
🎀 Low fuel pressure due to pump issues (indirect cause)

Symptoms

Hard starting

Engine stalling

Poor acceleration

Rough idle

Reduced fuel economy

“Check Engine” light on

How to Diagnose (Step-by-Step)

1. Scan for additional codes

If you also have P0089, P0087, P0190–P0193, they may point to related fuel pressure issues.

2. Inspect the fuel pressure regulator connector

Look for corrosion, loose pins, broken wires.

3. Check wiring continuity

Ensure no open or short circuits between the regulator and the ECM.

4. Test the Fuel Pressure Regulator

Use a multimeter to check resistance.

Replace if readings are out of spec.

5. Measure actual fuel pressure using a gauge

Compare with manufacturer specs.

6. Check Fuel Pump operation

Weak pump = unstable pressure = circuit DTCs.

7. PCM test

Only after all other components check out.

Common Fixes

⭐ Replace faulty fuel pressure regulator
⭐ Repair/replace damaged wiring harness
⭐ Clean or tighten electrical connectors
⭐ Replace fuel rail pressure sensor (if also faulty)
⭐ Replace fuel pump (if pressure is low)
⭐ Reprogram or replace ECM (last resort)

If you meant “P00900” specifically

There is no standard OBD-II code P00900.
If your scanner is showing P00900, it may be a manufacturer-specific extended code. Tellme the vehicle brand, model, year, and I can give an exact interpretation.

Welcome To Madurai Car Service 💐🙏🏻.