Fix P2068: Mechanic’s solutions that WORKED

The code P2068: Fuel Level Sensor “B” Circuit High points out a fault in the secondary fuel level sensor circuit, suggesting it’s sending an unexpectedly high signal. This issue is most likely caused by a problem with the sensor itself, its wiring, or the instrument cluster interpreting its signal.

P2068 quick overview

Meaning	P2068: Fuel Level Sensor “B” Circuit High
Is it serious?	This code indicates a problem with the fuel gauge readings, which isn’t immediately dangerous but can lead to misjudging fuel levels and potential breakdowns if not addressed.
Possible causes	– Faulty or incorrect installation of the fuel level sender “B” – Damaged or corroded wiring and connectors to the sender – Faulty instrument cluster or gauge stepper motors – Outdated vehicle computer software – Physical obstruction or sticking of the sender’s float arm
How to diagnose?	Identify Sender “B”: Confirm which sender is designated as “B” in your vehicle, typically the secondary or driver’s side sender. Check Wiring and Connectors: Inspect all related wiring and connectors for damage or corrosion. Test Sender Operation: Use a multimeter to test the sender’s resistance and operation directly. Monitor via Scan Tool: Utilize a scan tool to monitor fuel level readings from both senders. Consult TSBs and Software Updates: Check for any Technical Service Bulletins or software updates that may address known issues. Inspect Instrument Cluster: Consider potential issues with the instrument cluster, especially if there’s a history of similar problems.

How to fix P2068 – learn from mechanics

I looked into P2068 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: Chevrolet

Vehicle Information:
2005 Chevrolet C4500 Kodiak C4E042 6.6L

Issue + Repair History:

• The fuel gauge stays at empty with PCM Code P2068 (Secondary Fuel Sending Unit Voltage High).
• After clearing PCM codes, the gauge works briefly, then returns to empty when the code reappears.
• The vehicle doesn’t have a factory secondary tank.
• Removed/repaired aftermarket wiring.

Other OBD2 Codes + Test Results:

• P2068: Secondary Fuel Sending Unit Voltage High
• Primary fuel tank sending unit: Tests OK

Suggestions to Fix Issue:

• Check for a connector where a second tank might be and inspect for a short to power.
• Consider reprogramming the PCM to address potential software issues.
• Ensure software is set for a single tank configuration.
• Explore potential wiring or PCM issues related to the fuel gauge.

Final Fix:

• Reprogramming the vehicle’s computer at the dealer resolved the issue, indicating it was a software-related problem.

Case #2: Ford

Vehicle Information:
2009 Ford Flex SE 3.5L

Issue + Repair History:

• The vehicle displayed a code for the 2nd fuel level sensor, P2068.
• The code was initially cleared by another shop but returned intermittently about a week and a half later.
• Replaced the level sensor with an OEM part, but the light continued to come on after two starts.
• Connections at the tank and harness were rechecked; ohms showed contact for the 2nd level sensor.
• Advised the customer to replace and reprogram the instrument cluster due to potential failures.

Other OBD2 Codes + Test Results:

• P2068: Fuel level sensor circuit high
• B2627: 2nd fuel level sensor

Suggestions to Fix Issue:

• Confirm if the PCM might have identified the wrong sending unit.
• Check wiring directly to the instrument cluster; consider issues with the cluster itself.
• For vehicles with a saddle tank, ensure both sending units are functioning correctly.
• Consider the possibility of sulfites in fuel causing bad connections on the sending unit card, potentially rectified with Techron additive.

Final Fix:

• Replacing the fuel pump fuel level sensor resolved the issue, as it had an open circuit likely caused by drying out.
• The instrument cluster had incorrectly identified the wrong sensor, which should have been B1202, not P2068.

Case #3: Hyundai

Vehicle Information:
2008 Hyundai Santa Fe SE 3.3L

Issue + Repair History:

• After replacing both left and right fuel level senders, the fuel gauge only rose to the halfway mark.
• The Check Engine Light turned on with code P2068 indicating a fault with sender “B” circuit.
• Despite testing and rechecking the wiring and connections, the issue persisted.
• Initially uncertain which sender was “B,” later confirmed to be the driver’s side.

Other OBD2 Codes + Test Results:

• P2068: Sending unit “B” circuit fault

Suggestions to Fix Issue:

• Check resistance levels for both left and right senders to ensure they are within specifications.
• Ensure the float hasn’t got caught or installed incorrectly during installation.
• Use a scan tool to monitor fuel level pids for both sending units and observe the float movements.
• Verify the orientation of sender “B,” ensuring it’s not installed backward.
• Consider the possibility that one of the senders might have been installed upside down.

Final Fix:

• The issue was resolved with a new sender “B” (driver’s side), correcting the fuel gauge reading and eliminating the P2068 code.
• A bad part from the dealer was identified as the cause, and the correct orientation of the sender was crucial for proper function.

Case #4: Ford

Vehicle Information:
2006 Ford Five Hundred Limited 3.0L

Issue + Repair History:

• The vehicle came in stalling due to low fuel pressure.
• After replacing the fuel pump assembly on the passenger side of the gas tank, the gas gauge would not read full despite filling up the tank.

Related Repair History:

• Removed and replaced the fuel pump assembly on the passenger side of the gas tank.

Suggestions to Fix Issue:

• Review TSB 06-17-2 related to fuel gauge issues and MIL with various DTCs.
• Check grounds to the sending unit to ensure they are not faulty.
• Confirm if the sender-only side (likely the driver’s side) was plugged in correctly.
• Note that both senders must send a signal for accurate reading; consider quality issues with aftermarket parts.
• Recheck plugs and connections for any issues.
• Consider that the replacement unit might be faulty.

Final Fix:

• Replacing the sending unit on the driver’s side resolved the issue.
• After replacing the unit and refilling the gas tank, the fuel gauge read correctly.

Case #5: GMC

Vehicle Information:
2004 GMC Sierra 3500 6.6L

Issue + Repair History:

• The vehicle came in stalling, diagnosed with low fuel pressure due to a failed fuel pump.
• After replacing the fuel pump assembly, the fuel gauge would not read full and the truck wouldn’t transfer fuel to the front tank.
• The gauge had been inoperative for 5 years, and the transfer issue was new.

Related Repair History:

• Removed, tested, and replaced the transfer pump.

Suggestions to Fix Issue:

• Review TSBs for gauge issues, particularly 05-06-04-008a.
• Check connections and grounds to the sending unit, especially if the problem started after pump replacement.
• Verify that both senders (pump/sender side and sender-only side) are plugged in and functioning.
• Consider stepper motor issues in the cluster or other cluster problems.
• Perform a balance pump test and monitor the fuel level PID via a scanner.
• Check the PCM for the latest software updates and ensure both senders are recognized.
• Look into known issues with the float arm getting stuck or the front tank overfilling.
• Consider the possibility of a wiring issue, especially if there was prior damage.

Final Fix:

• The problem was resolved by replacing the cluster and both senders, followed by programming at the local dealer.

Common Advice	Brief Description of Diagnostic Step
Check Both Senders	Ensure both the primary and secondary fuel level senders are functioning correctly and are properly connected.
Replace Faulty Sender(s)	If one or both senders are found to be faulty, replace them with OEM or quality aftermarket parts.
Verify Wiring and Connections	Check all related wiring and connectors for damage, corrosion, or loose connections that could affect sender operation.
Consult TSBs and Recalls	Look up any Technical Service Bulletins or recalls that might address known issues with the fuel system or gauges.
Use Diagnostic Tools	Utilize scan tools to monitor fuel level PID and sender operation to pinpoint the issue.
Consider Cluster Issues	Investigate potential issues with the instrument cluster, especially the gauge stepper motors or circuitry.
Check for Software Updates	Ensure the vehicle’s computer software is up-to-date, as outdated software can lead to erroneous readings.
Inspect for Physical Obstructions	Ensure nothing is physically obstructing the sender’s float arm or causing it to stick, misread, or install incorrectly.