The OBD2 code P2149 is associated with a fault in the fuel injector group “B” supply voltage circuit, indicating an issue with the power supply to the injectors in one of the engine’s banks. This problem can lead to various symptoms, including misfires, poor idle quality, and potentially the engine running in a degraded mode.
It’s particularly critical in vehicles with advanced fuel injection systems, such as those found in diesel engines, where precise control over fuel delivery is essential for proper operation and emissions control.
P2149 quick overview
| Meaning | P2149: Fuel Injector Group “B” Supply Voltage Circuit/Open |
| Is it serious? | Yes, it directly impacts engine performance and can lead to increased emissions, reduced fuel efficiency, and, in some cases, the engine not running. |
| Possible causes | – Faulty wiring or connectors in the injector circuit – Issues with the Fuel Injector Control Module (FICM) – Poor electrical grounds – Damaged fuel injectors causing resistance out of specifications |
| How to diagnose? | Inspect the wiring and connectors for damage, corrosion, or loose connections affecting the injector circuit Check the Fuel Injector Control Module (FICM) for proper operation, including power supply and ground connections Test the fuel injectors for resistance and compare to manufacturer specifications Examine the vehicle’s grounding points for potential issues affecting circuit integrity |
P2149 Meaning
For those not deeply familiar with automotive systems, fuel injectors are like the heartbeats of an engine, delivering precise amounts of fuel to the combustion chamber. The P2149 code suggests a problem in the electrical pathway that powers half of these heartbeats, potentially causing uneven engine running or a noticeable lack of power.
It’s akin to a runner trying to compete with one leg tied; the engine can’t perform at its best because not all injectors are receiving the power they need. Fixing this issue typically involves electrical diagnostics to trace and repair faults within the circuit, ensuring all injectors can operate correctly and in harmony.
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How to fix P2149 – learn from mechanics
I looked into P2149 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case 1: Dodge
Vehicle Information 2007 Dodge Ram 3500 ST 5.9L
Issue + Repair History
- Experienced vibration resembling a misfire; scanned ECM showing codes P0204 and P2149.
- Replaced injector #4 but vibration persisted; further road testing suggested a potential balance issue related to the dual mass flywheel.
- Continued misfire on cold startup, accompanied by check engine light and code P2149 indicating group 2 injector voltage problem.
- Detected voltage fluctuation corresponding with activation of air intake heater; disconnected heater power wire to mitigate issue.
- Replaced both batteries after testing revealed one was faulty, but problem persisted.
- Discovered loose pin (#57) in harness connecting ECM, leading to intermittent code P2149 and misfire.
- Injector resistance test revealed high resistance in one injector; replaced faulty injector.
Other OBD2 Codes + Test Results
- P0204: Injector #4 Open
- P0304: Cylinder #4 Misfire
- P2149: Group 2 Voltage Low/Open
Mechanic Suggestions
- Measure resistance of the intake heater and compare with specifications.
- Check for shorts in injector harness and ensure terminal nuts are clear of any contact with the valvetrain.
- Perform resistance test on all injectors and compare values, ensuring they fall within the specified range.
- Consider the firing order when diagnosing injector-related issues; code for #4 cylinder might correspond to #6 in firing order.
- Block injectors individually and check for leak down to ensure proper function.
Final Fix
- Replaced faulty injector and addressed loose pin in ECM harness, resolving misfire and voltage issue associated with group 2 injector.
Case #2: Chevrolet
Vehicle Information 2004 Chevrolet Silverado 2500 HD 6.6L
Issue + Repair History
- Replaced injector wiring harness pig tails for cylinders #2, #3, #7, and #8.
- Vehicle returned with codes P0202, P0205, and P2149 after approximately 300 miles.
- Followed diagnostic flow chart from “AllData” but suspected a faulty FICM.
- Discovered a 1-inch wide ground strap at the rear of the driver’s head to the firewall was cut in half, likely due to rubbing on the glow plug mounting bracket.
- Replaced ground strap with a 4 ga. starter wire and extended its length to avoid contact with the glow plug mounting bracket.
- Test drove for 62 miles at all speeds; codes did not return.
Other OBD2 Codes + Test Results
- P0202: Injector Circuit Fault Cylinder #2
- P0205: Injector Circuit Fault Cylinder #5
- P2149: Injector Position Voltage Control Circuit, Group 2
Mechanic Suggestions
- Check grounds at the back of the engine and on the left side near the power steering pump.
- Inspect wire harness at the top of the FICM for rubbing and shorting issues.
- Check for wiring rub-through in the area of the alternator bracket.
- Perform resistance testing on grounds and check for any loose connections.
Final Fix
- Replaced damaged ground strap at the rear of the driver’s head to the firewall, eliminating rubbing on the glow plug mounting bracket, and test drove the vehicle to confirm that the codes did not return.
Case #3: GMC
Vehicle Information 2005 GMC Sierra 3500 SLT 6.6L
Issue + Repair History
- Initially diagnosed with code P2149, experiencing poor idle quality, surging, cutting out, and misfires.
- Replaced injector control module (FICM), which temporarily resolved the issue for about a month.
- Problem recurred, leading to suspicion of a faulty FICM.
- Replaced FICM again, resolving all issues.
Other OBD2 Codes + Test Results
- P2149: Injector Position Voltage Control Circuit, Group 2
Mechanic Suggestions
- Check wiring harness for chafing and rubbing, particularly near the alternator bracket, FICM bracket, and injector connectors.
- Utilize resources like YouTube for visual guides and service bulletins like 09-06-04-034 for additional troubleshooting steps.
- Consider using online resources such as BBB Industries for wiring diagrams and technical service bulletins.
- Check for potential grounds issues and ensure proper grounding to prevent module failures.
Final Fix
- Replaced the injector control module (FICM), resolving all issues with poor idle quality, surging, cutting out, and misfires.
How to diagnose P2149
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Diagnostic Step | Explanation |
|---|---|
| Inspect wiring and connectors | Look for any signs of damage, corrosion, or loose connections. |
| Check the FICM | Verify the module’s operation, including its power and ground. |
| Test the fuel injectors | Measure resistance and ensure it falls within specifications. |
| Examine vehicle grounding points | Identify and rectify any potential issues with electrical grounds. |
Addressing a P2149 code involves a thorough inspection and testing of the fuel injection system’s electrical components, from the wiring and connectors to the control module and injectors themselves. Given the complexity of modern fuel systems, especially in diesel engines, accurately diagnosing and fixing the root cause of this code is crucial for restoring optimal engine performance and reliability.
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko
I have a problem with my 2009 Mercedes Vito, code P2149 , can I fix this thanks David