03-02-2025
14 min.
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P2155 Fuel Injector Group "D" Supply Voltage Circuit/Open

The P2155 Fuel Injector Group "D" Supply Voltage Circuit/Open diagnostic trouble code indicates that the Engine Control Module (ECM/PCM) has detected an open circuit or interruption in the electrical supply circuit associated with Fuel Injector Group "D".

In simple terms, the vehicle's computer is detecting that the expected electrical supply to a particular group of fuel injectors is missing, interrupted, or electrically disconnected.

Fuel injectors require a reliable electrical circuit to operate correctly. If the injector supply circuit is open, one or more injectors may not receive the electrical power they need. This can cause incorrect fuel delivery, engine misfires, rough running, hard starting, loss of power, increased emissions, or even engine stalling.

The exact meaning of Fuel Injector Group "D" is manufacturer-specific. Group D may represent a particular group of cylinders, injector bank, shared power circuit, or manufacturer-defined injector circuit. It should not be assumed to refer to the same cylinders on every vehicle.

What Does P2155 Mean?

P2155 means that the ECM/PCM has detected a problem with the supply-voltage circuit for Fuel Injector Group D, specifically an open or interrupted circuit.

An open circuit means that electrical current cannot flow through the intended path.

The interruption may occur because of:

Broken wiring
Disconnected connector
Blown fuse
Faulty injector relay
Damaged fuse-box terminal
Corroded connector
Loose electrical terminal
Failed power-distribution circuit
Damaged injector harness
Incorrect wiring repair
Failed electrical component

In some cases, the problem may affect the entire injector group. In others, only part of the circuit may be interrupted.

What Is Fuel Injector Group D?

Fuel injectors are electrically controlled components that deliver fuel into the engine.

Modern engines can have multiple injector circuits, and manufacturers may divide these circuits into different groups.

The designation "D" is not universally standardized.

Depending on the vehicle, Group D may refer to:

Several fuel injectors
A particular cylinder bank
A shared injector power supply
A specific injector circuit
A manufacturer-defined injector group

Therefore, the exact location of the affected circuit should be confirmed using:

Vehicle make
Model
Model year
Engine type
Wiring diagram
Manufacturer service information

This is important because replacing an injector without identifying the actual open circuit may not solve P2155.

How Does a Fuel Injector Circuit Work?

A typical fuel injector has an electrical circuit that allows the ECM to control injector operation.

In many systems, several injectors receive power from a shared supply circuit.

The ECM then controls the injector by switching the circuit electronically.

When the injector is commanded on, its internal solenoid or actuator operates and allows fuel to enter the engine.

The ECM determines injector operation using information from sensors such as:

Crankshaft position sensor
Camshaft position sensor
Mass airflow sensor
Manifold pressure sensor
Throttle position sensor
Engine coolant temperature sensor
Oxygen sensors
Fuel-pressure sensors

A reliable power supply and control circuit are essential.

If the supply circuit is open, the affected injector may not operate even if the injector itself is mechanically perfect.

Symptoms of P2155

Symptoms depend on how many injectors are affected and where the circuit is interrupted.

Check Engine Light

The Check Engine Light will commonly illuminate when P2155 is stored.

Engine Misfire

If one or more injectors stop operating, the affected cylinders may misfire.

Possible symptoms include:

Engine shaking
Uneven running
Loss of smoothness
Hesitation
Poor acceleration

Rough Idle

An engine with one or more non-functioning injectors may idle roughly.

The severity depends on the number of affected cylinders.

Hard Starting

If the affected injector group is essential for starting, the engine may require extended cranking.

In severe cases, the engine may fail to start.

Engine Stalling

If enough injectors lose power, the engine may stall.

Reduced Engine Power

The engine may have significantly less power, particularly during acceleration.

Poor Acceleration

The vehicle may hesitate or feel weak because the engine is not receiving the correct amount of fuel.

Poor Fuel Economy

Fuel delivery may become unbalanced, reducing combustion efficiency.

Engine Vibration

Misfiring cylinders can cause noticeable vibration.

Increased Exhaust Emissions

Incomplete combustion can increase exhaust emissions.

Fuel Smell

Depending on the failure and injector control strategy, abnormal fuel delivery may produce a fuel smell.

Reduced-Power Mode

Some vehicles may enter a protective engine-management strategy.

Multiple Warning Lights

Severe engine-performance problems can sometimes cause additional warnings, such as:

Traction-control warning
Stability-control warning
Reduced-power warning

Common Causes of P2155

Several electrical problems can interrupt the fuel injector Group D supply circuit.

Broken Injector Wiring

A broken wire is one of the most direct causes of an open circuit.

Possible causes include:

Engine vibration
Harness movement
Heat damage
Chafing
Previous repairs
Accidental damage

A wire may break internally while its insulation remains visually intact.

Disconnected Injector Connector

A connector that is not fully seated can interrupt power to an injector or injector group.

This may happen after:

Engine repair
Injector replacement
Transmission work
Wiring service
Engine removal or installation

Corroded Connector

Corrosion increases electrical resistance and can eventually interrupt the circuit.

Look for:

Green corrosion
Oxidized terminals
Water contamination
Damaged terminal surfaces
Poor terminal tension

Blown Injector Fuse

Many vehicles supply injector power through a dedicated fuse.

A blown fuse can interrupt power to multiple injectors.

The underlying reason for the blown fuse must be identified.

Possible causes include:

Short circuit
Failed injector
Damaged wiring
Electrical overload

Simply replacing the fuse without finding the cause can result in another failure.

Faulty Injector Relay

Some fuel-injection systems use a relay to supply power to injectors.

A faulty relay may cause:

No injector power
Intermittent injector operation
Open supply circuit
Voltage loss

Damaged Fuse-Box or Relay Terminals

The injector power circuit may pass through a fuse or relay box.

Problems can include:

Burned terminals
Loose contacts
Corrosion
Water intrusion
Damaged internal connections

High-Resistance Electrical Connection

A poor connection may appear electrically connected but fail when the injector circuit is under load.

Possible causes include:

Loose terminals
Corroded terminals
Poor splices
Damaged connectors
Partially broken wires

Voltage-drop testing is useful for identifying these faults.

Short Circuit

Although P2155 specifically identifies an open or supply-circuit problem, a short circuit may cause the fuse protecting the injector supply to blow.

The result can then appear as an open injector power circuit.

Faulty Fuel Injector

An injector with an internal electrical failure can interrupt or overload a shared supply circuit.

Possible injector faults include:

Internal open circuit
Internal short circuit
Damaged solenoid
Incorrect resistance
Incorrect injector specification

However, the injector should be tested rather than automatically replaced.

Incorrect Injector Installation

An incorrectly installed injector or connector can interrupt the electrical supply.

Possible issues include:

Connector not locked
Wiring trapped under components
Damaged terminal
Incorrect injector
Harness incorrectly routed

Damaged Engine Wiring Harness

The injector harness is exposed to harsh conditions.

Possible causes include:

Exhaust heat
Oil contamination
Water
Vibration
Engine movement
Abrasion

A damaged harness can create an intermittent or permanent open circuit.

Poor Engine or Chassis Ground

Although the injector supply side may be the primary concern, poor grounds can also create abnormal electrical conditions.

Inspect:

Battery ground
Engine ground strap
Chassis ground
ECM ground circuits

Aftermarket Electrical Modifications

Modified vehicles may have altered injector circuits.

Potential causes include:

Aftermarket ECU
Engine swap
Performance wiring
Modified fuel system
Incorrect wiring adapters

ECM/PCM Problem

The ECM/PCM controls the injector system.

An internal control-module problem is possible but generally less common than:

Wiring problems
Fuse problems
Relay problems
Connector faults
Injector problems
Power-distribution faults

The ECM/PCM should be considered only after external circuits have been tested.

Vehicles Commonly Affected by P2155

P2155 can occur on many OBD-II vehicles using electronically controlled fuel injectors and manufacturer-defined injector groups.

Examples can include:

Ford F-150
Ford Mustang
Ford Explorer
Ford Escape
Ford Fusion
Chevrolet Silverado
Chevrolet Tahoe
Chevrolet Suburban
Chevrolet Camaro
GMC Sierra
GMC Yukon
Cadillac Escalade
Dodge Ram
Dodge Charger
Dodge Challenger
Jeep Grand Cherokee
Jeep Wrangler
Toyota Tundra
Toyota Sequoia
Toyota Tacoma
Nissan Titan
Nissan Armada
Nissan Pathfinder
Honda Pilot
Honda Accord
Honda Civic
BMW 3 Series
BMW 5 Series
Mercedes-Benz E-Class
Volkswagen Passat
Audi A4
Audi A6

This list is not exhaustive.

Important: The exact definition and physical location of Fuel Injector Group D can vary by manufacturer, engine, and model year.

A vehicle-specific wiring diagram should always be used.

How Is P2155 Diagnosed?

Diagnosis should focus on finding exactly where the injector Group D supply circuit is interrupted.

Scan for Additional Trouble Codes

Start with a complete scan of the vehicle.

Look for:

P2155
P2156
P2157
Other injector circuit codes
Cylinder misfire codes
Fuel-system codes
Battery-voltage codes
Charging-system codes
ECM/PCM communication codes

Additional codes can help determine whether the problem is isolated to the injector group or part of a larger electrical fault.

Check Freeze-Frame Data

Review the conditions under which P2155 was stored.

Useful information includes:

Engine RPM
Vehicle speed
Battery voltage
Engine load
Coolant temperature
Fuel-system status

If the code appeared during engine starting, inspect the injector power circuit and battery voltage carefully.

Identify Fuel Injector Group D

Before testing components, determine exactly which injectors belong to Group D.

Use the vehicle's wiring diagram to identify:

Affected injectors
Common power supply
Injector control wires
Fuse
Relay
Power-distribution module
ECM/PCM terminals

This prevents unnecessary injector replacement.

Check the Injector Fuse

Inspect the appropriate fuse.

If it is blown:

Do not repeatedly replace the fuse.
Check the injector harness.
Check the affected injectors.
Check for shorts.
Inspect the relay and power-distribution circuit.

The cause of the fuse failure must be corrected.

Check Injector Relay Operation

If a relay supplies injector power, verify:

Relay input voltage
Relay output voltage
Relay control
Relay contact condition
Voltage drop across the relay

A relay can fail internally even when it appears normal externally.

Measure Injector Supply Voltage

With the correct ignition and engine conditions, check for voltage at the affected injector group.

Compare the result with:

Battery voltage
Other injector groups
Manufacturer specifications

If no voltage is present, trace the circuit backward toward the fuse, relay, and power-distribution system.

Perform a Continuity Test

Check continuity through the relevant supply circuit with the circuit safely isolated according to manufacturer procedures.

An open reading can help identify:

Broken wire
Disconnected connector
Damaged terminal
Fuse-box problem
Harness interruption

Perform Voltage-Drop Testing

Voltage-drop testing can identify resistance in:

Power wiring
Relay contacts
Fuse connections
Connectors
Ground circuits

This is often more useful than a simple continuity test because a circuit can have continuity while still failing under electrical load.

Inspect Injector Wiring

Carefully inspect the Group D harness.

Look for:

Broken wires
Chafing
Melted insulation
Exposed conductors
Corrosion
Poor splices
Previous repairs
Wiring pulled tight around engine components

Pay special attention to areas near the exhaust.

Inspect Injector Connectors

Inspect every affected injector connector for:

Loose terminals
Bent pins
Corrosion
Water intrusion
Broken locking tabs
Poor terminal tension

A connector that looks connected may still have poor electrical contact.

Test Individual Injectors

Where appropriate, test injector electrical characteristics.

Possible tests include:

Coil resistance
Current draw
Injector actuation
Electrical waveform

Compare the affected injector with manufacturer specifications and known-good components.

Do not rely on a generic injector resistance value, because injector specifications differ between engines.

Check Injector Control Signals

Use suitable diagnostic equipment to inspect the injector control waveform.

This can help distinguish between:

Supply-circuit problems
Injector faults
ECM driver faults
Wiring problems

Check Battery and Charging System

Verify that the vehicle has stable electrical voltage.

Check:

Battery condition
Battery terminals
Alternator output
Charging voltage
Ground connections

Low system voltage can contribute to multiple electrical faults.

Check ECM/PCM Power and Grounds

Verify that the ECM/PCM receives proper:

Battery power
Ignition power
Ground

A module with an unstable power or ground supply may produce misleading diagnostic codes.

Check for Aftermarket Modifications

Inspect any modifications involving:

ECU
Fuel injectors
Engine harness
Fuel system
Performance electronics

Incorrect modifications can interrupt the injector supply circuit.

How to Fix P2155

The correct repair depends on the fault found during diagnosis.

Repair Broken Wiring

Repair or replace broken injector supply wires.

The repaired wiring should be properly protected and routed away from heat and moving components.

Reconnect or Replace Damaged Connectors

If an injector connector is disconnected, reconnect it correctly.

If terminals or the connector housing are damaged, replace the affected components.

Replace a Blown Fuse After Finding the Cause

A blown fuse should not simply be replaced without determining why it failed.

Once the underlying fault has been corrected, install the correct fuse specified for the vehicle.

Replace a Faulty Injector Relay

If testing confirms that the injector relay is defective, replace it with the correct relay.

Repair Fuse-Box or Power-Distribution Problems

Damaged fuse-box terminals, relay contacts, or power-distribution wiring should be repaired.

Repair High-Resistance Connections

Clean, repair, or replace corroded or loose terminals and poor electrical connections.

Repair a Short Circuit

If a short caused the injector fuse to fail, locate and repair the short before restoring the circuit.

Replace a Faulty Fuel Injector

If an injector is confirmed to have an internal electrical fault, replace the affected injector with the correct specification.

Restore Proper Grounds

Repair poor battery, engine, chassis, or ECM grounds.

Correct Aftermarket Wiring

Any incorrectly modified injector wiring should be restored to the appropriate manufacturer configuration.

Repair or Replace the ECM/PCM

The ECM/PCM should only be considered after the injector supply circuit, fuse, relay, wiring, connectors, injectors, power, and grounds have been properly tested.

What Happens If P2155 Is Ignored?

Ignoring P2155 can lead to significant engine-performance problems if the injector group is not operating correctly.

Possible consequences include:

Engine misfires
Rough running
Hard starting
Engine stalling
Reduced power
Poor acceleration
Increased fuel consumption
Increased emissions
Catalytic-converter damage from prolonged misfires
Additional electrical problems

If the open circuit affects multiple injectors, the engine may run extremely poorly or fail to start.

Can You Drive With P2155?

Driving with P2155 is not recommended for an extended period, particularly if the engine is misfiring or running poorly.

A short trip may be possible if:

The engine starts normally.
The engine runs smoothly.
No severe misfire is present.
The Check Engine Light is not flashing.
Vehicle performance remains normal.

However, the problem should be diagnosed promptly.

Avoid driving if you experience:

Severe engine shaking
Flashing Check Engine Light
Major loss of power
Repeated engine stalling
Strong fuel smell
Multiple warning lights

A flashing Check Engine Light can indicate a severe misfire capable of damaging the catalytic converter.

Is P2155 a Serious Code?

P2155 is generally considered a moderate-to-high severity diagnostic trouble code, depending on how many injectors are affected.

The code itself does not necessarily indicate internal engine damage.

However, an open injector supply circuit can cause one or more cylinders to operate without the correct fuel delivery.

This can result in:

Misfires
Poor combustion
Reduced engine performance
Increased emissions
Catalytic-converter damage

If the entire injector group loses power, the vehicle may become undrivable.

How to Prevent P2155

Injector circuit problems cannot always be prevented, but regular maintenance can reduce the risk.

Recommended practices include:

Inspect engine wiring during routine service.
Protect injector wiring from exhaust heat.
Keep electrical connectors clean and secure.
Repair damaged wiring promptly.
Maintain battery terminals.
Maintain engine and chassis grounds.
Replace fuses only with the correct specification.
Inspect injector connectors after engine repairs.
Use correct replacement injectors.
Secure wiring harnesses away from moving parts.
Avoid poorly designed electrical modifications.
Address charging-system problems quickly.
Do not ignore Check Engine Light warnings.

P2155 vs. Related Injector Codes

Code	General Description
P2155	Fuel Injector Group "D" Supply Voltage Circuit/Open
P2156	Fuel Injector Group "D" Supply Voltage Circuit Low
P2157	Fuel Injector Group "D" Supply Voltage Circuit High
P0200	Injector Circuit Malfunction
P0201–P0208	Injector Circuit/Open for a specified cylinder
P0300	Random/Multiple Cylinder Misfire
P0301–P0308	Misfire detected on a specified cylinder

The main difference is that P2155 identifies an open or interrupted supply circuit, while P2156 indicates low supply voltage and P2157 indicates high supply voltage.

Final Thoughts

The P2155 Fuel Injector Group "D" Supply Voltage Circuit/Open diagnostic trouble code indicates that the ECM/PCM has detected an interruption or open circuit in the electrical supply associated with Fuel Injector Group D.

Common causes include:

Broken injector wiring
Disconnected connectors
Corroded terminals
Blown injector fuse
Faulty injector relay
Damaged fuse-box connections
High-resistance electrical connections
Short circuits that have caused a fuse to open
Faulty fuel injector
Incorrect injector installation
Damaged engine harness
Poor electrical grounds
Aftermarket wiring modifications
ECM/PCM problems

The correct diagnostic approach is to first identify exactly which injectors belong to Group D on the specific vehicle. The technician should then check the fuse and relay, verify injector supply voltage, perform continuity and voltage-drop tests, inspect the wiring and connectors, test the affected injectors, and verify ECM/PCM power and ground circuits.

P2155 does not automatically mean that a fuel injector needs to be replaced. An open wire, disconnected connector, blown fuse, faulty relay, damaged fuse-box terminal, or wiring problem can all produce this code.

Finding the exact point where the electrical supply is interrupted is the key to repairing P2155 correctly and restoring reliable fuel-injection operation.