OBD-II trouble code
P2068: Fuel Level Sensor "B" Circuit High
The secondary fuel level signal has climbed above its ceiling. The half of the circuit that causes it most often is the half almost nobody measures — the sender's own ground path — and the error direction matters, because a gauge that lies upward is the one that strands people.
Quick facts
- System
- Powertrain
- Category
- Fuel System
- Severity
- Low severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $90 – $950
- DIY difficulty
- Intermediate DIY
Browse every code in P2000–P20E8, or start from the full code library.
What does P2068 mean?
P2068 is stored when the signal from the second fuel level sender sits above the highest value the module is willing to accept. On a resistive sender that ceiling is reached when the loop through the sender stops carrying current, so the reading rises toward the module's internal supply and stays there.
What makes this member worth its own page is that the loop has two sides and only one of them gets tested. Everyone follows the signal wire. But a resistive sender divides a voltage between the module's internal resistor and itself, and that division is only meaningful if the sender's return sits at true chassis potential. Raise the return by half a volt and the reported level rises with it, without a single fault anywhere on the signal side.
On a vehicle with a secondary sender that return is very often not the same ground the main pump module uses. The far lobe or the second tank has its own plastic housing, its own flange, and its own ground lead run to a body or frame stud somewhere underneath — frequently an eyelet added where the second tank was plumbed in, sitting in the worst environment on the vehicle. Salt gets to it, the eyelet swells with corrosion, and the connection gradually develops resistance long before it fails outright. This is why a P2068 whose signal wire tests perfect from end to end is so often a ground problem, and why a continuity check finds nothing: corrosion that reads a few ohms on a meter with no current flowing can drop a meaningful voltage once the circuit is live. The measurement that finds it is a voltage drop taken between the sender's ground pin and battery negative with everything connected and awake.
The direction of the error is the second thing this code carries that its low-side twin does not, and it is the reason to fix it rather than live with it. A secondary sender pinned near full feeds an overstatement into the cluster's arithmetic. Total fuel is calculated from both inputs, so the needle and the distance-to-empty are not obviously wrong — they are plausibly wrong, reading a quarter tank when there is almost nothing there. On a saddle-tank vehicle the lobe the pump draws from is the one that empties first, so the engine can cut out on a slope with the gauge still showing a reserve the driver has every reason to trust. A gauge that lies downward is an annoyance. A gauge that lies upward gets someone stopped on a hard shoulder.
There is one cause worth ruling out before anything is back-probed. On a good many designs the sender signal and the fuel pump's battery feed occupy the same connector shell on top of the tank. A chafe or a wet bridge inside that shell can put full system voltage onto a circuit built to read a few volts, which is capable of damaging the module input it lands on. So the first measurement on a high code is simply what voltage is actually present on the signal pin. A reading near the module's pull-up value is an ordinary open. A reading near battery voltage is a short to power, and that changes both the urgency and the list of things that need checking afterwards.
Common causes
- Corroded or high-resistance ground lead at the secondary tank or lobe
- Open signal wire between the module and the secondary sender
- Connector unseated or terminal backed out at the tank-top connector
- Resistance track in the secondary sending unit worn through or broken
- Float arm detached, so the wiper has left the track entirely
- Short to battery voltage from the fuel pump feed sharing the same connector shell
- Failed internal joint or crimp inside the sending unit assembly
- Ground eyelet added during a dual-tank installation left unprotected and rusted
- Damaged pin or spread terminal following previous fuel pump or tank work
- Aftermarket sending unit whose full-scale resistance exceeds the module's accepted range
Symptoms
- Fuel gauge reading full or higher than the vehicle actually holds
- Gauge needle refusing to fall as fuel is used
- Distance-to-empty staying implausibly high or not counting down
- Running out of fuel while the gauge still shows a reserve
- Engine cutting out on a slope or in a corner with fuel apparently remaining
- Check engine light on with the engine running normally
- Low fuel warning never illuminating
- Gauge accepting far less fuel at a fill than the reading implied
- Fault appearing after tank, pump or rear suspension work
- Fault worse in winter or after road salt exposure
Diagnostic steps
- 1.Measure the actual voltage on the secondary sender's signal pin before anything else. A value near the module's pull-up voltage is an open circuit; a value near battery voltage is a short to power and needs tracing before any component is replaced.
- 2.Measure voltage drop across the sender's ground path with the circuit live — sender ground pin to battery negative. More than about 0.2 volts here will lift the reading on its own and is the single most overlooked cause of this code.
- 3.Inspect the dedicated ground lead and eyelet for the secondary tank or lobe. On dual-tank vehicles it is often a separate stud under the body, and corrosion there is common and cheap to fix.
- 4.Jumper the signal pin to a known good ground at the sender connector. If the reported level immediately drops to zero, the signal wire and the module are healthy and the fault is the sender or its ground. If it stays high, the open is between that connector and the module.
- 5.Check the tank-top connector for a spread, backed-out or corroded terminal before condemning the sending unit — a terminal that has lost its grip produces exactly this code and costs almost nothing.
- 6.If the sender is accessible, measure its resistance directly and sweep the float arm through full travel. An infinite reading anywhere in the sweep confirms a broken track.
- 7.Compare the primary and secondary readings after an overnight settle. On a saddle tank the two should bear a sensible relationship; one at the ceiling with the other sensible localises the fault to the secondary circuit.
- 8.Ask what work the vehicle has had. A code that appeared after pump, tank, exhaust or suspension work points at a disturbed connector or a pinched lead rather than a failed component.
- 9.If battery voltage was found on the signal circuit, check the module input for damage after repairing the short — an input that has been overdriven may not recover.
- 10.Relieve fuel pressure and disconnect the battery before opening any tank access panel, and follow proper fuel handling precautions throughout.
Repair cost
$90 – $950
Diagnosis runs $90 to $180. Cleaning and re-terminating a corroded ground eyelet is the cheapest genuine outcome at $60 to $150 and resolves a meaningful share of these. Repairing an open or a chafe in the harness between the module and the tank is $150 to $450, toward the top when the tank has to be lowered to reach the damage. A replacement secondary sending unit is $60 to $350 in parts with 0.7 to 1.5 hours of labour where an access panel exists, or 2 to 3.5 hours where the tank must come down; where the manufacturer sells only a complete pump and sender module, parts rise to $250 to $700. If battery voltage reached the signal circuit, allow for the possibility that the module input was damaged, which is a separate and much larger repair.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with fuel level sensor / sending unit replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.