P0086
Stop drivingThe engine computer detects a voltage signal from the Fuel Rail Pressure Sensor 'B' circuit that is too high.
Code P0086 means the fuel rail pressure sensor 'B' circuit has a high voltage signal. Common causes: Faulty sensor (60%), wiring issues (30%). Drivability: No, stop driving. Repair cost: $100-$300 DIY, $200-$600 professional.
Can I Drive With P0086?
No, stop driving
Immediate repair needed
Stop driving immediately if: Engine stalls, will not start, or runs extremely rough.
Symptoms of P0086
- 1Check Engine Light is on
- 2Engine cranks but does not start
- 3Engine stalls shortly after starting
- 4Rough idling
- 5Reduced engine power or acceleration
- 6Engine misfires
- 7Poor fuel economy
Common Causes of P0086
Parts most likely causing this code, ranked by probability
The sensor itself is faulty, sending an incorrect high voltage signal to the engine computer.
60% of P0086 cases are fixed by replacing this part
A short to voltage in the sensor's wiring harness or a corroded/damaged connector causes the engine computer to read an abnormally high signal.
30% of P0086 cases are fixed by repairing wiring or connectors
The engine computer has an internal fault that incorrectly interprets the sensor's signal or has a faulty internal circuit.
5% of P0086 cases are fixed by replacing the ECM/PCM
Corrosion or a loose connection at the sensor or ECM can lead to erratic high voltage readings.
5% of P0086 cases are fixed by cleaning or securing connections
Check These First (Before Buying Parts)
- Visually inspect the fuel rail pressure sensor 'B' and its electrical connector for any visible damage, corrosion, or loose connections.
- Check the wiring harness leading to the sensor for any signs of chafing, cuts, or shorts to other wires.
How to Diagnose P0086
- 1Connect an OBD-II scanner to confirm P0086 and check for other related codes.
- 2Visually inspect the fuel rail pressure sensor 'B' and its wiring harness for any obvious damage, fraying, or corrosion.
- 3Check the electrical connector at the sensor for bent pins, corrosion, or looseness.
- 4Using a multimeter, test the voltage at the sensor connector to ensure proper reference voltage and ground.
- 5Monitor the fuel rail pressure sensor 'B' live data with a scan tool; look for abnormally high or erratic readings.
- 6If possible, disconnect the sensor and check the voltage on the signal wire to the ECM; if it still reads high, the issue is in the wiring or ECM.
P0086 on Popular Vehicles
Ford F-150
2011-2024Ford F-150s with EcoBoost engines are known to have issues with fuel system sensors and their wiring due to the high-pressure direct injection system. Inspect the sensor and connector carefully for heat damage or corrosion.
70% fixed by replacing sensor or repairing wiring
Chevrolet Silverado
2007-2024Silverados, particularly those with direct injection V8s or Duramax diesels, can experience P0086 due to sensor failure or wiring chafing near the fuel rail. Check for physical damage to the harness.
65% fixed by replacing sensor or repairing wiring
Ram 1500
2013-2024Ram 1500s, especially EcoDiesel models, are susceptible to fuel system sensor issues. P0086 often indicates a bad sensor or a short in the sensor's circuit. Verify sensor readings with a scan tool.
68% fixed by replacing sensor or repairing wiring
Frequently Asked Questions
What does P0086 mean?
P0086 indicates that the engine's computer has detected a voltage signal from the 'B' fuel rail pressure sensor circuit that is higher than expected.
Can I drive with P0086?
No, stop driving. This code indicates a critical issue with your fuel system. Driving with P0086 can lead to severe engine damage, a no-start condition, or leave you stranded.
Will P0086 clear itself?
No, P0086 will not clear itself. This is a hard fault that requires diagnosis and repair. The Check Engine Light will remain on until the underlying issue is resolved and the code is cleared with a scan tool.
How do I fix P0086 myself?
Start by visually inspecting the sensor and its wiring for damage. If the wiring looks good, you will likely need to replace the fuel rail pressure sensor 'B'. You will need a scan tool to confirm the sensor reading and clear the code.
How much does it cost to fix P0086?
DIY repair costs for P0086 typically range from $100 to $300 for a new fuel rail pressure sensor. Professional repair at a shop will cost between $200 and $600, including parts and labor.
P0086 keeps coming back - why?
If P0086 keeps returning, it means the root cause was not fully addressed. This often happens if the wiring issue was misdiagnosed as a sensor problem, or if there's an intermittent short in the harness that wasn't found. In rare cases, the ECM itself could be at fault.
Will P0086 fail emissions/smog test?
Yes, P0086 will cause your vehicle to fail an emissions or smog test. The Check Engine Light being on is an automatic failure in most jurisdictions, and a critical fuel system fault like this directly impacts emissions.
What's the difference between P0086 and P0087?
P0086 indicates a 'circuit high' condition for the fuel rail pressure sensor 'B', meaning the voltage signal is too high. P0087 indicates 'fuel rail/system pressure - too low', meaning the actual fuel pressure is below specification, which could be caused by a faulty sensor, pump, or regulator.
P0086 on Ford F-150?
On Ford F-150s, especially EcoBoost models, P0086 often points to a faulty fuel rail pressure sensor or issues with its wiring harness due to engine bay heat or vibration. Start with a thorough inspection of the sensor and its connector.
Questions to Ask Your Mechanic
Did you check the actual voltage output of the fuel rail pressure sensor 'B' with a multimeter, not just the scan tool reading?
Good answer: Yes, I confirmed the sensor's signal wire is showing an abnormally high voltage, even when disconnected from the sensor, which points to a wiring short or ECM issue.
What did you find when inspecting the wiring harness for the fuel rail pressure sensor 'B'?
Good answer: I found a section of the wiring harness was chafed and shorting to a nearby power wire, causing the high voltage signal. I repaired the harness.
Repair Cost Estimate
DIY Repair
Parts only
$100-$300
Shop Repair
Parts + labor
$200-$600
Save $100-$300 by doing it yourself
Difficulty
intermediate
Time
1-3 hours
Intermediate - requires a scan tool and multimeter for proper diagnosis, and comfort with electrical testing.
Cost of Waiting
Ignoring P0086 can lead to a complete no-start condition, severe engine misfires, and potential damage to other fuel system components or the catalytic converter due to incorrect fuel delivery. A $100 sensor replacement now prevents a $1,000+ repair later.
While You're In There...
While not directly related to a 'circuit high' code, if you are working on the fuel system, it's a good time to replace the fuel filter if it's due for maintenance and easily accessible.
Tools You'll Need
- OBD-II scan tool
- Multimeter
- Basic hand tools (sockets, wrenches)
- Wire strippers/crimpers (if wiring repair is needed)
P0086 points to a specific electrical issue in your fuel system. While critical, it's often a straightforward sensor or wiring repair that will get your engine running smoothly again.
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Your Next Steps
Step 1: Perform a thorough visual inspection of the fuel rail pressure sensor 'B' and its entire wiring harness. Look for any signs of damage, corrosion, or wires shorting to other components.
Step 2: If the visual inspection doesn't reveal an obvious issue, use an OBD-II scan tool to monitor the live data from the fuel rail pressure sensor 'B'. If the reading is consistently high or erratic, disconnect the sensor and test the voltage on the signal wire to the ECM with a multimeter. If the voltage remains high with the sensor disconnected, the issue is in the wiring harness or the ECM.
Step 3: If the wiring and ECM check out, replace the fuel rail pressure sensor 'B'. Clear the code and test drive the vehicle to confirm the repair.