OBD-II Diagnostic Trouble Code
P2149 — Fuel Injector Group B Supply Voltage Circuit/Open
P2149 means the ECM detected an open circuit or general fault on the supply voltage circuit for injector group B. The ECM may see no current flow through the shared high-side feed for the injectors in that group.
Severity 4/5
Truck-relevant
Stop within 50 mi
Severity
Stop within 50 mi
Fuel Injector Group B Supply Voltage Circuit/Open
Code
P2149
Category
Powertrain
Subsystem
Fuel
Truck-relevant
Yes
What this means for truckers
P2149 (Fuel Injector Group B Supply Open) — second injector group supply open circuit.
Before you replace parts — try this first
P2149 on the Fuel system is most often open injector harness or loose injector pass-through connector — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
Several cylinders may stop firing, causing a rough run, heavy misfire, loss of power, white smoke or a no-start. The check-engine light is on and multiple injector or misfire codes often appear together.
Common causes
- CommonOpen injector harness or loose injector pass-through connector ($200–$900)
- OccasionalBroken wire or loose terminal nut on an injector in group B ($150–$700)
- OccasionalOpen injector solenoid ($500–$1800)
- RareECM injector driver fault ($1200–$3500)
How to fix
Check the injector harness connector at the ECM and engine pass-through for loose or damaged pins
When to use: First step
Measure continuity from the ECM supply pin through the harness to each injector in group B
When to use: To locate the open
Check individual injector solenoid resistance
When to use: When harness continuity is good
Replace the ECM
When to use: Only after confirming harness and injectors are good
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P2100 — Throttle Actuator Control Motor Circuit/Open
- → P2101 — Throttle Actuator Control Motor Circuit Range/Performance
- → P2127 — Throttle/Pedal Position Sensor/Switch E Circuit Low Input
- → P2128 — Throttle/Pedal Position Sensor/Switch E Circuit High Input
- → P2138 — Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation
Frequently Asked Questions
Can I drive with code P2149?
Drive with caution. P2149 is severity 4 — stop within ~50 miles. Most commercial diesel codes at this severity (turbo, fuel rail, transmission solenoid) can damage adjacent expensive components if left unrepaired. Get to a service location before highway-speed loads.
How much does it cost to fix P2149 on a commercial truck?
Total repair cost ranges $150–$3500 depending on the root cause. The cheapest fix is usually the first one listed below — Open injector harness or loose injector pass-through connector — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P2149 fail a DOT inspection?
P2149 itself doesn't automatically fail an inspection, but if the truck is in reduced-power mode (limp mode) at the time of inspection, it WILL be flagged. Most inspectors will note the check engine light but pass the truck if it's running and performance is normal. Fix it before a Level 1 inspection regardless.
What's the difference between P2149 and related codes?
P2149 is closely related to: P2100 (Throttle Actuator Control Motor Circuit/Open), P2101 (Throttle Actuator Control Motor Circuit Range/Performance), P2127 (Throttle/Pedal Position Sensor/Switch E Circuit Low Input), P2128 (Throttle/Pedal Position Sensor/Switch E Circuit High Input). These codes share the same subsystem (fuel) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P2149 is set without the companions, the issue is more isolated.
How do I prevent P2149 from coming back after a repair?
For P2149 (Fuel Injector Group B Supply Voltage Circuit/Open), prevention centers on the fuel system. Replace fuel filters at the OEM interval — don't stretch them. Use only diesel from high-volume fuel stops (avoid bottom-of-tank fuel at low-traffic stations). Add a water separator if you don't have one. After repair, prime the fuel system per the engine manual.