P2635 2018 GMC Sierra Code - Fuel Pump Flow Performance
Quick Answer
The Engine Control Module (ECM) supplies voltage to the fuel pump driver control module when the ECM detects that the ignition is on. Common causes include Faulty Fuel Pump, Fuel Pump harness is open or shorted, Fuel Pump circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P2635 2018 GMC Sierra indicates Fuel Pump Flow Performance.
- Common causes
- Common causes include Faulty Fuel Pump, Fuel Pump harness is open or shorted, Fuel Pump circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P2635 2018 GMC Sierra Description
The Diagnostic Trouble Code (DTC) will be set when the fuel pump driver control module detects a difference of ± 60 kPa (8.7 PSI) at 400 kPa (58 PSI) request or ±45 kPa (6.5 PSI) at 300 kPa (43.5 PSI) request between the desired fuel pressure and the actual fuel pressure for approximately 10 s.
What are the Possible Causes of the DTC P2635 2018 GMC Sierra?
- Faulty Fuel Pump
- Fuel Pump harness is open or shorted
- Fuel Pump circuit poor electrical connection
- Faulty Fuel Pump Control Module (if applicable)
How to Fix the DTC P2635 2018 GMC Sierra?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
Code Tech Notes
- 2014-2018 Chevrolet Silverado
- 2015-2018 Chevrolet Suburban
- 2015-2018 Chevrolet Tahoe
If the Diagnostic Trouble Codes (DTC) P2635, U0074, and/or U18A2 are set, it may be found that the actual fuel pressure (low-pressure system) will be reading substantially higher than desired fuel pressure, in this case, the cause of the problem is a loss of communication between Engine Control Module (ECM) and Fuel Pump Control Module (FPCM).
- Diagnose for any communication DTCs set (U0074 would take priority over U18A2 if both set) before addressing DTC P2635.
- If DTC P2635 is not resolved by correcting the communication DTCs, only then should diagnose the DTC P2635.
- It has been found that a communication issue between the FPCM and ECM can potentially induce DTC P2635 and result in a pressure differential between actual and desired fuel system pressures.
- If the actual fuel pressure is substantially higher than desired (10 psi / 70 kPa or more), replacement of the fuel pump control module or fuel system components typically will not resolve this issue.
- If the actual fuel pressure is substantially lower than desired (10 psi / 70 kPa or more), this Factory Service Bulletin would NOT apply. It would be recommended to diagnose low actual fuel pressure.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P2635 2018 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
Need more information about the P2635 2018 GMC Sierra code?
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Frequently Asked Questions about P2635 2018 GMC Sierra Code
1. What are the common symptoms of OBDII code P2635 in a 2018 GMC Sierra related to fuel pump flow performance?
- Common symptoms include poor engine performance, rough idling, stalling, and reduced fuel efficiency.
2. What are the possible causes of OBDII code P2635 in a 2018 GMC Sierra?
- The code P2635 may be triggered by a faulty fuel pump, clogged fuel filter, fuel pressure regulator issues, or wiring/connectivity problems.
3. How can I diagnose the root cause of OBDII code P2635 in my 2018 GMC Sierra?
- Diagnostic steps typically involve checking the fuel pump operation, inspecting the fuel filter for blockages, testing the fuel pressure regulator, and examining the wiring for any damages.
4. Is it safe to continue driving my 2018 GMC Sierra with OBDII code P2635 present?
- It is not recommended to drive the vehicle with code P2635 as it can lead to further damage to the fuel system and potential engine issues.
5. Can I reset OBDII code P2635 in a 2018 GMC Sierra by disconnecting the battery?
- While disconnecting the battery may clear the code temporarily, it is crucial to address the underlying issue causing the code to prevent it from reoccurring.
6. Will a fuel system cleaner help resolve OBDII code P2635 in my 2018 GMC Sierra?
- Using a fuel system cleaner may improve fuel system performance but is unlikely to resolve the specific issue triggering code P2635. Professional diagnosis and repair are recommended.
7. How much does it typically cost to repair OBDII code P2635 in a 2018 GMC Sierra?
- The cost of repair can vary depending on the exact cause of the issue, but it may involve replacing the fuel pump, fuel filter, or addressing wiring problems. Costs can range from a few hundred to over a thousand dollars.
8. Can a DIY enthusiast fix OBDII code P2635 in a 2018 GMC Sierra, or is it best left to a professional mechanic?
- While some basic troubleshooting steps can be done by DIY enthusiasts, diagnosing and repairing OBDII code P2635 often requires specialized tools and expertise, making it advisable to consult a professional mechanic.
9. Will ignoring OBDII code P2635 in my 2018 GMC Sierra lead to more serious problems over time?
- Ignoring code P2635 can lead to fuel delivery issues, potential engine damage, and decreased vehicle performance, making it important to address the problem promptly.
10. Are there any preventive maintenance measures I can take to avoid OBDII code P2635 in my 2018 GMC Sierra?
- Regularly changing the fuel filter, using high-quality fuel, and following the manufacturer's recommended maintenance schedule can help prevent issues that may trigger code P2635.
Discuss the causes and fixes for P2635 2018 GMC Sierra OBDII Code
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On the 2018 GMC Sierra, unfortunately the fuel pump is located inside the tank, so you do have to drop the fuel tank to replace it—unless you cut an access panel, which isn’t recommended unless you're really experienced and know exactly where to cut.
Dropping the tank is the safest and cleanest way to do it. Make sure to relieve the fuel pressure first and drain as much fuel as possible to make the job easier. If you're just trying to clean out bad fuel or debris, there are also service ports and fuel line disconnects you can use to flush the system without pulling the tank. Let me know what you’re trying to do exactly, and I can guide you further.
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