P228A Fuel Pressure Regulator 1 – Forced Engine Shutdown

How severe is this DTC?

Since insufficient/excessive fuel pressure can damage the internal engine and catalytic converter and lead to various driving issues, a P228A code should be classified as severe.

What are some of the symptoms of the code?

Symptoms of a P228A fault code may include:

No start condition
Engine misfire codes and idle control codes may also accompany a P228A
Reduced fuel efficiency
Delayed starting when the engine is cold
Black smoke from the exhaust system

What are some common causes of the code?

Causes of this code may include:

Low engine oil level/pressure
Engine improperly timed
Faulty fuel pressure sensor
Faulty fuel pressure regulator
Shorted or open wiring or connectors in the fuel pressure regulator control circuit
Incorrect PCM or PCM programming error

What are the troubleshooting steps for P228A?

You will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information to accurately diagnose a P228A code.

You can save time by looking for Technical Service Bulletins (TSBs) that match the recorded code, the vehicle (year, make, model, and engine), and the symptoms presented. This information can be found in your vehicle information source. If you find the right TSB, it might provide a quick solution to your diagnosis.

After connecting the scanner to the vehicle’s diagnostic port and retrieving all stored codes and relevant freeze frame data, note the information (in case the code turns out to be intermittent). After that, clear the codes and test the vehicle until one of two things happens; the code is restored or the PCM enters readiness mode.

The code may be more difficult to diagnose if the PCM enters readiness mode at this point, as the code is intermittent. The condition that caused the P228A to be stored may need to worsen before an accurate diagnosis can be made. If the code is restored, continue with the diagnosis.

You can obtain connector face views, connector pinout diagrams, component location diagrams, wiring diagrams, and diagnostic flowcharts (related to the code and the specific vehicle) using your vehicle information source.

Perform a visual inspection of the associated wiring and connectors. Repair or replace any wiring that is cut, burned, or damaged.

Use the DVOM to test the voltage and ground circuits at the electronic fuel regulator (1) and fuel pressure sensors. If no voltage is detected, check the system fuses. Replace any blown or faulty fuses as needed and retest.

If voltage is detected, test the corresponding circuit at the PCM connector. If no voltage is detected there, suspect an open circuit between the sensor in question and the PCM. If voltage is found there, suspect a PCM programming error or faulty PCM.

Test the fuel pressure regulator and fuel pressure sensor with the DVOM. If either does not meet the manufacturer’s specifications, consider it faulty.

If the fuel regulator (1) and sensor(s) appear to be functioning correctly, use a manual pressure gauge to test the actual fuel pressure on the rail to replicate the failure condition.

The fuel rail and associated components may be under (extremely) high pressure
Be cautious when removing the fuel pressure sensor or fuel pressure regulator
Fuel pressure tests should be performed with the ignition switch in the Key On Engine Off (KOEO) position

P228B Fuel Pressure Regulator 2 – Engine Forced Shutdown

How serious is this DTC?

Since insufficient/excessive fuel pressure can damage the internal engine and converter and lead to various driving issues, a P228B code should be classified as serious.

What are some of the symptoms of the code?

Symptoms of a P228B fault code may include:

No start condition
Engine misfire codes and idle control codes may also accompany a P228B
Reduced fuel efficiency
Delayed starting when the engine is cold
Black smoke from the exhaust system

What are some common causes of the code?

Causes of this code may include:

Low engine oil level/pressure
Engine improperly timed
Faulty fuel pressure sensor
Faulty fuel pressure regulator
Shorted or open wiring or connectors in the fuel pressure regulator control circuit
Incorrect PCM or PCM programming error

What are the troubleshooting steps for P228B?

You will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information to accurately diagnose a P228B code.

The code may be more difficult to diagnose if the PCM enters readiness mode at this point, as the code is intermittent. The condition that caused the P228B to be stored may need to worsen before an accurate diagnosis can be made. If the code is restored, proceed with the diagnosis.

You can obtain connector face views, connector pinout charts, component location diagrams, wiring diagrams, and diagnostic flowcharts (related to the code and the specific vehicle) using your vehicle information source.

Perform a visual inspection of the associated wiring and connectors. Repair or replace any wiring that is cut, burned, or damaged.

Use the DVOM to test the voltage and ground circuits at the electronic fuel regulator (2) and fuel pressure sensors. If no voltage is detected, check the system fuses. Replace any blown or faulty fuses as needed and retest.

Test the fuel pressure regulator and fuel pressure sensor with the DVOM. If either does not meet the manufacturer’s specifications, consider it faulty.

If the fuel regulator (2) and sensor(s) appear to be functioning correctly, use a manual pressure gauge to test the actual fuel pressure on the rail to replicate the failure condition.

The fuel rail and associated components may be under (extremely) high pressure
Be cautious when removing the fuel pressure sensor or fuel pressure regulator
Fuel pressure tests should be performed with the ignition switch in the Key On Engine Off (KOEO) position

P228C Fuel Pressure Regulator 1 Control Exceeded Limits – Pressure Too Low

Explanation of Code P228C: “Fuel Pressure Regulator Malfunction”

Severity

Level: 🔴 High (risk of engine and catalytic converter damage).
Urgency:
Hard starting (especially when cold).
Risk of knocking/pre-ignition (piston damage).

Common Symptoms

🚨 Check engine light on (MIL) with code P228C and associated codes (P0300, P0171).
⛽ Excessive fuel consumption (black smoke from exhaust).
🐌 Loss of power under load.
🔄 Unstable idle or cold stalling.

Main Causes

Fuel pressure problems:

Faulty pressure regulator (stuck or internal leak).
Defective fuel pressure sensor (incorrect readings).

Mechanical problems:

Weak fuel pump or clogged filter.
Incorrect timing (improperly set timing belt/chain).

Electrical failures:

Short circuit/open in the regulator circuit.
Faulty PCM (software or hardware error).

Diagnostic Procedure (Detailed Steps)

Step 1: Search for TSBs (Technical Service Bulletins)

Example: TSB 18-NA-355 for some GM vehicles (fuel pressure regulator issues).

Step 2: Fuel Pressure Test

Tools: High-pressure gauge (e.g., OEM 25365) + rail adapter.
Procedure:

Connect the gauge to the rail’s Schrader valve.
Ignition ON (KOEO) → Pressure should reach 4-6 bar (gasoline) / 300-400 bar (diesel).
If pressure is low: Check pump, filter, and regulator.

Step 3: Pressure Regulator Test

Multimeter:
Measure regulator resistance (typical value: 10-20 Ω).
Check supply voltage (12V) and PCM signal (PWM signal).

Step 4: PCM Circuit Inspection

Continuity: Test wires between regulator and PCM.
Short circuits: Check for no contact with ground or +12V.

Solutions & Costs

Problem	Solution	Average Cost
Faulty pressure regulator	Replacement	€100 – €300
Faulty pressure sensor	Replacement	€80 – €200
Weak fuel pump	Replacement	€300 – €800
PCM reprogramming	Software update	€100 – €350

Mistakes to Avoid

❌ Forgetting to depressurize the system: Risk of fuel spray (follow safety procedures).
❌ Ignoring engine timing: Check timing with a cam gauge.

Frequently Affected Models

Volkswagen Golf TSI (1.4L/2.0L): Faulty regulator.
Ford Focus EcoBoost: Pressure sensor issues.
Opel Insignia (2.0L CDTi): Internal regulator leaks.

Practical Case

Problem: Code P228C on a Peugeot 308 1.6 THP with black smoke.
Diagnosis: Pressure regulator stuck in open position.
Solution: Regulator replacement (€220) + injector cleaning.

Pro Tips

Use an advanced scanner: View the PID “Fuel Rail Pressure” for real-time data.
Test under load: Reproduce the fault by driving at 3000 RPM to observe pressure.

If the problem persists, consult a professional equipped with high-pressure diagnostic tools (e.g., Bosch FSA 720)! 🔧🚗⛽

P228D Fuel Pressure Regulator 1 Control Exceeded Limits – Pressure Too High

How serious is this DTC?

Since insufficient/excessive fuel pressure can damage the internal engine and catalytic converter and lead to various driving issues, a P228D code should be classified as serious.

What are some of the symptoms of the code?

Symptoms of a P228D trouble code may include:

Engine misfire codes and idle control codes may also accompany a P228D
Reduced fuel efficiency
Delayed starting when the engine is cold
Black smoke from the exhaust system

What are some common causes of the code?

Causes

of this code may include:

The engine is not timed correctly
Low engine oil pressure
Faulty fuel pressure sensor
Faulty fuel pressure regulator
Shorted or open wiring or connectors in the fuel pressure regulator control circuit
Incorrect PCM or PCM programming error

What are the troubleshooting steps for P228D?

You will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information to accurately diagnose a P228D code.

You can save time by searching for Technical Service Bulletins (TSBs) that match the recorded code, the vehicle (year, make, model, and engine), and the symptoms presented. This information can be found in your vehicle information source. If you find the right TSB, it might provide a quick solution to your diagnosis.

The code may be more difficult to diagnose if the PCM enters readiness mode at this point, as the code is intermittent. The condition that caused the P228D to be stored may need to worsen before an accurate diagnosis can be made. If the code is restored, proceed with the diagnosis.

You can obtain connector face views, connector pinout diagrams, component location diagrams, wiring diagrams, and diagnostic flowcharts (related to the code and the vehicle in question) using your vehicle information source.

Perform a visual inspection of the associated wiring and connectors. Repair or replace any wiring that is cut, burned, or damaged.

Test the fuel pressure regulator and fuel pressure sensor with the DVOM. If either does not meet the manufacturer’s specifications, consider it faulty.

If the fuel regulator (1) and sensor(s) appear to be functioning correctly, use a manual pressure gauge to test the actual fuel pressure at the rail to reproduce the failure condition.

The fuel rail and associated components may be under (extremely) high pressure
Be cautious when removing the fuel pressure sensor or fuel pressure regulator
Fuel pressure tests should be performed with the ignition switch in the Key On Engine Off (KOEO) position

P228E Fuel Pressure Regulator 1 Exceeded Learning Limits – Too Low

How severe is this DTC?

Since insufficient/excessive fuel pressure can damage the internal engine and catalytic converter and lead to various driving issues, a P228E code should be classified as severe.

What are some of the symptoms of the code?

Symptoms of a P228E trouble code may include:

No start condition
Engine misfire codes and idle control codes may also accompany a P228E
Reduced fuel efficiency
Delayed starting when the engine is cold
Black smoke from the exhaust system

What are some common causes of the code?

Causes

of this code may include:

Engine not timed correctly
Low engine oil pressure
Faulty fuel pressure sensor
Faulty fuel pressure regulator
Shorted or open wiring or connectors in the fuel pressure regulator control circuit
Incorrect PCM or PCM programming error

What are the troubleshooting steps for P228E?

You will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information to accurately diagnose a P228E code.

The code may be more difficult to diagnose if the PCM enters readiness mode at this point, as the code is intermittent. The condition that caused the P228E to be stored may need to worsen before an accurate diagnosis can be made. If the code is restored, proceed with the diagnosis.

You can obtain connector face views, connector pinout charts, component location diagrams, wiring diagrams, and diagnostic flowcharts (related to the code and the vehicle in question) using your vehicle information source.

Perform a visual inspection of the wiring and associated connectors. Repair or replace wiring that is cut, burned, or damaged.

Use the DVOM to test the voltage and ground circuits at the electronic fuel regulator (1) and fuel pressure sensors. If no voltage is detected, check the system fuses. Replace blown or faulty fuses as needed and retest.

Test the fuel pressure regulator and fuel pressure sensor with the DVOM. If either does not meet the manufacturer’s specifications, consider it faulty.

If the fuel regulator (1) and sensor(s) appear to be functioning correctly, use a manual pressure gauge to test the actual fuel pressure on the rail to reproduce the failure condition.

The fuel rail and associated components may be under (extremely) high pressure
Be cautious when removing the fuel pressure sensor or fuel pressure regulator
Fuel pressure tests should be performed with the ignition switch in the Key On Engine Off (KOEO) position

P228F Fuel Pressure Regulator 1 Control Limit Exceeded – Too High

How severe is this DTC?

Since insufficient/excessive fuel pressure can damage the internal engine and catalytic converter and lead to various driving issues, a P228F code should be classified as severe.

What are some of the symptoms of the code?

Symptoms of a P228F fault code may include:

No start condition
Engine misfire codes and idle control codes may also accompany a P228F
Reduced fuel efficiency
Delayed starting when the engine is cold
Black smoke from the exhaust system

What are some common causes of the code?

Causes

of this code may include:

The engine is not timed correctly
Low engine oil level/pressure
Faulty fuel pressure sensor
Faulty fuel pressure regulator
Shorted or open wiring or connectors in the fuel pressure regulator control circuit
Incorrect PCM or PCM programming error

What are the troubleshooting steps for P228F?

You will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information to accurately diagnose a P228F code.

The code may be more difficult to diagnose if the PCM enters readiness mode at this point, as the code is intermittent. The condition that caused the P228F to be stored may need to worsen before an accurate diagnosis can be made. If the code is restored, proceed with the diagnosis.

Perform a visual inspection of the associated wiring and connectors. Repair or replace any wiring that is cut, burned, or damaged.

Test the fuel pressure regulator and fuel pressure sensor with the DVOM. If either does not meet the manufacturer’s specifications, consider it faulty.

If the fuel regulator (1) and sensor(s) appear to be functioning correctly, use a manual pressure gauge to test the actual fuel pressure on the rail to reproduce the failure condition.

The fuel rail and associated components may be under (extremely) high pressure
Be cautious when removing the fuel pressure sensor or fuel pressure regulator
Fuel pressure tests should be performed with the ignition switch in the Key On Engine Off (KOEO) position

P2290 Injector Control Pressure Too Low

How severe is this DTC?

The conditions contributing to a stored P2290 code could lead to catastrophic engine damage. This is why this code must be classified as severe.

What are some symptoms of the code?

Symptoms of a P2290 fault code may include:

No start condition
Excessive exhaust smoke
Unusual engine compartment noises

What are some common causes of the code?

Causes

of this code may include:

Faulty high-pressure injection pressure sensor
Open or shorted control circuits
Low oil level
Low oil pressure

What are the troubleshooting steps for P2290?

Start by ensuring the engine is filled with oil to the proper level and that no oil pressure or oil level warning lights are illuminated. If this is the case, a manual oil pressure test may be necessary. Engine timing components are affected by engine oil pressure. High-pressure injection operation is actuated using engine timing components. If engine oil pressure is low, injection timing may be negatively affected.

You will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information to accurately diagnose a P2290 code.

You can save time by searching for Technical Service Bulletins (TSBs) that match the stored code, the vehicle (year, make, model, and engine), and the symptoms presented. This information can be found in your vehicle information source. If you find the right TSB, it might provide a quick solution to your diagnosis.

The code may be more difficult to diagnose if the PCM enters readiness mode at this point, as the code is intermittent. The condition that caused the P2290 to be stored may need to worsen before an accurate diagnosis can be made. If the code is restored, proceed with the diagnosis.

You can obtain connector face views, connector pinout charts, component location diagrams, wiring diagrams, and diagnostic flowcharts (related to the code and vehicle in question) using your vehicle information source.

Perform a visual inspection of the associated wiring and connectors. Repair or replace wiring that is cut, burned, or damaged.

Use the DVOM to test voltage and ground circuits at the injection system pressure sensors. If no voltage is detected, check the system fuses. Replace blown or faulty fuses as needed.

Test the injection pressure sensor with the DVOM. If it does not meet manufacturer specifications, consider it faulty.
Although this type of code is listed on some gasoline applications, I have seen it exclusively in diesel applications where an engine timing and/or lubrication issue had occurred.

P2291 Injector Control Pressure Too Low – Engine Start

📘 Code P2291 – Injector Control Pressure Too Low at Engine Start

How Severe Is This DTC Code?

Code P2291 is considered severe. It indicates that the pressure in the injector control circuit is insufficient, especially during startup. This situation can prevent the engine from starting properly or lead to serious damage, particularly in high-pressure diesel engines. It is therefore essential to address this issue immediately.

🔍 Symptoms Associated with Code P2291

Among the signs indicating the presence of this code, you may observe:

Inability to start the engine
Excessive exhaust smoke
Unusual sounds from the engine
Loss of power or irregular operation

🔧 Common Causes of Code P2291

This code can result from various mechanical or electrical issues. Here are the most common ones:

General Causes:

Faulty high-pressure fuel pressure sensor
Open, damaged, or short-circuited electrical circuit
Insufficient engine oil level
Low engine oil pressure

Specific Causes (e.g., Peugeot):

Air leak in the fuel circuit: loose fittings, damaged fuel filter, punctured line
Clogged fuel filter: restricts fuel supply to the pump
Running out of fuel: always check the fuel level
Faulty fuel pressure regulator: unable to maintain correct pressure
Failed high-pressure fuel pump: does not deliver the pressure required for injection
Leak in the high-pressure circuit: faulty injectors, rails, or lines
Electrical problem: damaged pressure sensor, wiring, or connectors

🛠️ Diagnostic and Repair Steps

Check the engine oil level and ensure no oil pressure or level warning lights are on.
Perform an oil pressure test if necessary. Low pressure can affect variable valve timing (VVT) and injection pressure.
Use an OBD2 scanner and a digital multimeter (DVOM), along with a reliable technical information source (RTA, TSB, etc.).

🧰 Detailed Procedure:

Look for any technical service bulletins (TSB) related to your vehicle.
Connect the scanner, retrieve codes and freeze frame data, then clear the codes to see if they return.
If the code returns immediately, continue diagnostics. Otherwise, it may be intermittent and require monitoring over time.
Visually inspect wiring and connectors related to the injection system. Repair any damaged, burnt, or loose cables.
Test the power and ground circuits of the pressure sensor using the DVOM. Also check associated fuses.
If the power supply is correct, test continuity between the sensor and the PCM (engine control module).
If voltage is present at the PCM but the code persists, suspect a software issue or a faulty PCM.
Test the injection pressure sensor: compare the obtained values with manufacturer specifications.

💡 Practical Tips:

You can reset the code temporarily by disconnecting the battery for a few minutes. Note that this only clears the code, not the problem.
If you are skilled in mechanics, you can perform the checks yourself. Otherwise, consult a qualified professional.
Do not drive for long with this code active: it could cause irreversible engine damage.

🔚 In Conclusion

Code P2291 is a clear indicator of a fuel pressure issue during startup, often encountered in modern diesel engines. When faced with this code, prompt and thorough diagnostics are essential to avoid costly repairs or even engine failure.

Irregular Injector Control Pressure

How severe is this DTC?

Conditions that contribute to a stored P2292 code could lead to catastrophic engine damage. This is why this code must be classified as severe.

What are some of the symptoms of the code?

Symptoms of a P2292 fault code may include:

No start condition
Excessive exhaust smoke
Unusual noises from the engine compartment

What are some common causes of the code?

Causes

of this code may include:

Faulty high-pressure injection pressure sensor
Open or shorted control circuits
Low oil level
Low oil pressure

What are the troubleshooting steps for P2292?

Start by ensuring the engine is filled with oil to the proper level and that no oil pressure or oil level warning lights are illuminated. If this is the case, a manual oil pressure test may be necessary. Engine timing components are affected by engine oil pressure. High-pressure injection operation is driven using engine timing components. If engine oil pressure is low, injection timing can be negatively affected.

You will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information to accurately diagnose a P2292 code.

The code may be more difficult to diagnose if the PCM enters readiness mode at this point, as the code is intermittent. The condition that caused the P2292 to be stored may need to worsen before an accurate diagnosis can be made. If the code is restored, proceed with the diagnosis.

Perform a visual inspection of the associated wiring and connectors. Repair or replace wiring that is cut, burned, or damaged.

Use the DVOM to test voltage and ground circuits at the injection system pressure sensors. If no voltage is detected, check the system fuses. Replace blown or faulty fuses as needed.

Test the injection pressure sensor with the DVOM. If it does not meet the manufacturer’s specifications, consider it faulty.

Although this type of code is listed on some gasoline applications, I have seen it occur exclusively in diesel applications where an engine timing and/or lubrication issue had occurred.

P2293 Fuel Pressure Regulator 2 Performance

Symptoms of a DTC P2293 may include:

Poor fuel economy
Poor acceleration or hesitation
Other codes may be present, such as lean O2 sensors
The engine light is on (malfunction indicator)

Potential causes of a P2293 fault code may include:

Fuel pump output
Clogged or pinched fuel lines / clogged fuel filter
Faulty regulator
Faulty fuel pressure sensor or electrical wiring

Possible Solutions

Fuel Pressure – Fuel pressure can be checked using a mechanical gauge attached to the fuel rail. If the fuel pressure meets factory specifications, there may be an issue with the fuel pressure sensor giving false readings to the PCM/ECM. If no fuel pressure test port is available, fuel pressure can only be checked using an advanced scan tool or by splicing adapter fittings between the fuel lines and the fuel rail.

Fuel Pump – The fuel pump output is determined by the PCM/ECM and may be controlled by an external fuel management computer. The fuel pump can be commanded on the duty cycle on vehicles equipped with returnless fuel systems. An advanced scan tool may be needed to check the output on these types of fuel systems. Test the fuel pump for sufficient power by locating the fuel pump wiring harness. Some vehicles may not be easily accessible to test the fuel pump wiring connections. Check the battery voltage at the positive terminal of the fuel pump using a digital volt-ohmmeter set to the volts scale with the positive lead on the power wire and the negative lead on a known good ground with the key in the on or run position. The fuel pump power wire may only be powered during engine cranking or the vehicle’s running state. The displayed voltage should be close to the actual battery voltage.

If power is insufficient, suspect the fuel pump wiring and trace it back to determine if there is excessive resistance in the wiring, loose wires, or loose/dirty connections. On return-type fuel pumps, the ground can be checked using the DVOM set to the ohms scale with one lead on the ground wire and the other lead on a known good ground. The resistance should be very low. On returnless fuel systems, the trigger wire can be checked using a graphing multimeter or oscilloscope set to the duty cycle scale. Typically, the fuel pump computer’s duty cycle will be double the commanded duty cycle controlled by the PCM/ECM. Using the graphing multimeter or oscilloscope, the positive lead will be connected to the signal wire and the negative lead to a known good ground; it may be necessary to determine which wire is correct using a factory wiring diagram. The actual duty cycle should be about double what the PCM/ECM commands; if the displayed duty cycle is half the amount, the settings on the DVOM may need to be adjusted to match the type of duty cycle being tested.

Fuel Lines – Look for physical damage or bent fuel lines that could cause a restriction in the fuel supply or return lines from the fuel pump. It may be necessary to remove the fuel filter to determine if the fuel filter is clogged and needs to be replaced; it should flow freely in the direction of flow indicated by an arrow on the fuel filter. Some vehicles are not equipped with fuel filters, and the filter is located at the inlet of the fuel pump itself; it will be necessary to remove the fuel pump module to determine if there is a lot of debris in the tank or if the fuel filter has been crushed or pinched, which could also restrict the fuel supply to the pump.

Regulator – On vehicles with a return fuel system, the regulator is usually located on the fuel rail itself. The fuel pressure regulator typically has a vacuum line that will mechanically restrict fuel based on the amount of vacuum provided by the engine. Check for damaged or loose vacuum hoses from the regulator. If the vacuum hose contains fuel inside, the regulator may have an internal leak that would cause a loss of pressure. Using a non-damaging clamp, the hose can be pinched after the fuel pressure regulator – if the fuel pressure is higher with a restriction on the return side of the regulator, the regulator may be at fault. On returnless systems, the fuel pressure regulator may be located inside the gas tank on the fuel pump module, and it may be necessary to replace the fuel pump module as a complete assembly.

Fuel Pressure Sensor – Test the fuel pressure sensor by removing the connector and checking the resistance between the terminals using the DVOM set to the ohms scale with the positive and negative leads on one of the connectors. The resistance should meet factory specifications. Check the fuel pressure sensor’s reference voltage with a factory wiring diagram to determine which wire powers the sensor using the DVOM set to the volts scale with the positive lead on the power wire and the negative lead on a known good ground. The voltage should be about 5 volts, depending on the vehicle.

If the voltage is not within specifications, trace the wiring to determine if there is excessive resistance in the wire supplying the sensor. The signal wire can be checked using the DVOM set to the volts scale with the positive lead connected to the signal wire and the negative lead on a known good ground with the vehicle turned on and running. The displayed voltage should match factory specifications based on the outside temperature and the internal fuel temperature inside the lines. The PCM/ECM converts the voltage to temperature to determine the actual fuel pressure. It may be necessary to check the voltage at the PCM/ECM harness connector to determine if there is a voltage difference. If the voltage at the PCM/ECM is not the same as the voltage displayed at the fuel pressure sensor, there may be excessive resistance in the wiring.

Disconnect the PCM/ECM harness connector and the fuel pressure sensor connector to check for excessive resistance using the DVOM set to the ohms scale with one lead at each end of the harnesses. The resistance should be very low; any excessive resistance may be a fault in the wiring, or there may be a short to power or ground. Look for a short to power by removing the PCM/ECM harness connection with the DVOM set to the volts scale, with the positive lead on the pin for the fuel pressure signal and the negative lead on a known good ground. If the voltage is the same as the reference or higher, there may be a short to power, and the wiring will need to be traced to determine where there is a short. Check for no short to ground by setting the DVOM to the ohms scale with one lead on the signal wire at the PCM/ECM harness connector and the other lead on a known good ground. If there is resistance, there may be a short to ground, and the wiring will need to be traced to determine where there is a short to ground.