P0090 on 2014-2020 Maserati Ghibli: Fuel Pressure Regulator Circuit Fixes

What's Unique About the 2014-2020 Maserati GHIBLI

For the Ghibli V6 and its platform-mates (Quattroporte V6, Levante V6), this code is frequently linked to a known issue with the electrical connector for the fuel pressure regulator. Maserati issued a Technical Service Bulletin (TSB MAS004191) and a Rapid Update (648) detailing a specific "wiggle test" to check for looseness in the connector pins, which can cause an intermittent open circuit due to engine vibrations. This suggests the problem is often not the regulator itself, but the small electrical part that connects to it, making proper diagnosis crucial to avoid unnecessary replacement of the entire high-pressure fuel pump.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on
• Reduced engine performance (limp mode)
• Delayed or hard starting
• Engine hesitation or stalling, sometimes randomly while driving
• Decreased fuel economy
• Black smoke from the exhaust
• Rough or unstable idle

Most Likely Causes

1. Faulty Fuel Pressure Regulator Connector 🔴 High Probability → Shop Fuel Injection Pressure Regulator Maserati issued TSB MAS004191 and Rapid Update 648 specifically to diagnose a poor connection at this connector, indicating it's a known failure point across the Ghibli, Quattroporte, and Levante V6 platforms due to a production deviation. Engine vibrations can cause the internal female pins to lose their grip on the male pins of the regulator solenoid.
   How to confirm: Perform the "wiggle test" as described in TSB MAS004191. After gaining access to the connector on the HPFP, disconnect it. Insert a special feeler tool (p/n 900100002) into each of the two female seats of the connector. Wiggle the tool to check for looseness. If the feeler does not remain firmly anchored in either seat, the connector is faulty and must be replaced.
   Typical fix: Replace the connector pigtail (Maserati part number 673015820) by splicing it into the existing engine harness. The TSB references another bulletin (MAS000766) for the proper wire soldering and heat-shrinking procedure.
   Est. part cost: $70-$120
2. Damaged Wiring Harness 🟡 Medium Probability The engine wiring harness can be susceptible to damage from heat, abrasion, or rodents.
   How to confirm: Visually inspect the wiring leading to the high-pressure fuel pump's regulator for any signs of chafing, breaks, melting, or corrosion. Use a multimeter to check for continuity between the ECM connector and the regulator connector. Also check for a steady voltage supply (typically a 5V reference or a 12V pulsed signal) with the key on.
   Typical fix: Repair the damaged section of the wire or replace the engine wiring harness if the damage is extensive.
   Est. part cost: $10-$800+
3. Failed Fuel Pressure Regulator Solenoid ⚪ Low Probability → Shop Fuel Injection Pressure Regulator
   How to confirm: The regulator is an integrated solenoid on the high-pressure fuel pump (HPFP). If the connector and wiring are confirmed to be good, the solenoid itself can be tested. Disconnect the harness and measure the resistance across the two pins of the solenoid with a multimeter. Compare this reading to the manufacturer's specification. An out-of-spec or infinite resistance reading (open circuit) indicates failure. A simple test involves briefly applying 12V to the solenoid pins; a healthy solenoid should make an audible click.
   Typical fix: Replace the entire high-pressure fuel pump assembly, as the regulator solenoid is integrated and not sold separately. The OEM part number for the HPFP is 336326 for 2014-2017 models.
   Est. part cost: $500-$1500

Rare But Worth Checking

• Faulty Engine Control Module (ECM): → Shop Engine Control Module (ECM) This is a very rare cause. Before condemning the ECM, all other possibilities, especially the common connector and wiring issues, must be exhaustively ruled out. An ECM failure would typically be diagnosed by confirming the wiring is perfect but there is no signal or voltage coming from the ECM pin for the regulator circuit.

Diagnosis Steps

1. Scan the vehicle for all stored DTCs. Note any other fuel-related codes like P0087, P0089, P0091, or P0092.
2. Obtain and carefully review Maserati Technical Service Bulletin MAS004191 / BOL 24-19. This document is the primary guide for this specific issue.
3. Locate the electrical connector for the fuel pressure regulator on the high-pressure fuel pump (HPFP). It is on the side of the pump, which is mounted to the engine.
4. Disconnect the 12V battery before proceeding with physical inspection.
5. Disconnect the connector and inspect for any visible damage, corrosion, or pushed-out pins.
6. Perform the "wiggle test" as described in the TSB using the specified feeler tool (p/n 900100002) to check for looseness in the connector's two female pins.
7. If the connector fails the test, the diagnosis is complete. Replace the connector pigtail (p/n 673015820).
8. If the connector passes the test, the connector itself is considered OK. Proceed to inspect the wiring harness between the connector and the ECM for damage.
9. Using a multimeter and wiring diagram, check for continuity and correct voltage on the control circuit to rule out a broken wire or short.
10. If wiring and the connector are confirmed good, test the resistance of the fuel pressure regulator solenoid itself. If it's out of specification, the HPFP assembly (p/n 336326) likely needs replacement.
11. As a final, unlikely step, the ECM's driver circuit may need to be tested by a specialist.

Parts You'll Likely Need

• Fuel Pressure Regulator Connector (OEM #673015820) — This is the most likely cause of the fault, as identified by a specific Maserati TSB. The connector's internal pins fail, causing an open circuit. It is a 5-wire pigtail kit.
  Trusted brands: Maserati OE
  OEM price range: $70-$120
• High-Pressure Fuel Pump (HPFP) (OEM #336326) — This is needed if the regulator solenoid, which is integrated into the pump, has failed. This is a less common cause than the connector. The part number 336326 applies to 2014-2017 models.
  Trusted brands: Bosch (OEM supplier), Maserati OE
  OEM price range: $1000-$1500
  Aftermarket price range: $500-$900

Related Codes That Often Appear With This One

• P0089 — P0089 indicates a performance issue with the fuel pressure regulator. It can appear alongside P0090 if the open circuit causes erratic regulator performance, leading to pressure deviations.
• P0091 — P0091 indicates the control circuit is shorted to ground (low voltage), which is an electrical fault related to the same circuit as P0090 (open circuit).
• P0092 — P0092 indicates the control circuit is shorted to power (high voltage), another electrical fault related to the same circuit as P0090.
• P0087 — P0087 (Fuel Rail/System Pressure - Too Low) can be a consequence of the P0090 fault, as the open circuit prevents the regulator from maintaining commanded pressure.

Technical Service Bulletins (TSBs) & Recalls

• MAS004191 / BOL 24-19: Diagnostic Sheet for DTC P0090 - Fuel Pressure Regulator Control Circuit 1 Open. Details the specific issue of a faulty connector and provides a wiggle-test procedure, feeler tool part number (900100002), and replacement connector part number (673015820). It explicitly names the Ghibli (M157), Quattroporte (M156), and Levante (M161) as affected models.

Platform-Specific Known Issues

• Maserati has issued Technical Service Bulletin MAS004191 / BOL 24-19 specifically for P0090 on the Ghibli V6, Quattroporte V6, and Levante V6. The bulletin provides a detailed diagnostic procedure to test the integrity of the fuel pressure regulator connector, which is a known weak point.
• Owners on forums like GhibliForum.com have reported experiencing this exact issue, with dealers often performing the TSB fix by replacing the connector pigtail to resolve the P0090 code and associated limp mode.

Mechanic-Grade Diagnostic Values

• Fuel Pressure Regulator (MSV) Control Current — expected: Greater than 0.7 Amps. Failure: A current value less than 0.7 A for more than 500 ms will trigger DTC P0090.
• Fuel Pressure Regulator Solenoid Resistance — expected: Approximately 2-4 Ohms (based on similar Bosch HPFP solenoids). Failure: An infinite resistance reading indicates an open circuit within the solenoid, requiring pump replacement. A reading far outside the expected range also indicates a fault.
• Voltage at Fuel Pressure Regulator Connector — expected: A pulsed voltage signal (PWM) from the ECM when the engine is running. A steady reference voltage (e.g., 5V or 12V) may be present with key-on, engine-off.. Failure: No voltage or a constant, non-pulsing voltage when running can indicate a wiring or ECM driver issue.

Scan Tool Commands That Help

• Maserati Diagnosi (MD) / Witech: High-Pressure Fuel Pump Actuator Test — This bidirectional test allows a technician to command the fuel pressure regulator solenoid to operate, verifying if the solenoid responds and if the control circuit from the ECM is functional. This can be used after confirming the connector and wiring are physically intact.
• Maserati Diagnosi (MD) / Witech: View Live Data: Desired vs. Actual Fuel Rail Pressure — While P0090 is an electrical circuit code, observing the fuel pressure data can provide context. If the actual pressure is fixed at a default value or doesn't respond to engine load changes, it supports the diagnosis of a non-functional regulator control circuit.

Wiring & Ground Locations

• High-Pressure Fuel Pump Connector — Located on the side of the high-pressure fuel pump (HPFP), which is mounted at the rear of the 3.0L V6 engine.. This 2-pin connector is the subject of TSB MAS004191 and is the most common failure point for P0090 due to a known manufacturing defect causing poor pin tension.
• Engine Ground Strap — The main engine-to-chassis ground strap is crucial for all engine electronics. While its exact location requires a workshop manual, it is typically a braided cable from the engine block to the frame rail.. A poor or corroded main engine ground can cause floating voltages and intermittent open circuit faults for various sensors and actuators, including the fuel pressure regulator circuit.

OEM Part Supersession History

• 310147, 336326 → 329202 — Part consolidation and potential design updates for the High-Pressure Fuel Pump (HPFP).
  Heads up: Part number 336326 is listed for 2014-2017 models, while 329202 is listed for 2017+ models, but they are often shown as interchangeable or part of a supersession chain. Always confirm with VIN.

Model Year Variations Within This Range

• 2014-2017: The original High-Pressure Fuel Pump part number is often cited as 336326 for these earlier models.
• 2017-2020: The High-Pressure Fuel Pump part number is often listed as 329202 for later models, though it appears to have superseded the earlier number.
• 2022-2023: TSB MAS004191 and Rapid Update 648 specifically call out MY22-23 vehicles for the connector pin tension issue, indicating the problem persisted or was identified in later production batches.