P0463 Code on a Buick: Fuel Level Sensor Circuit High (Buick Guide)

P0463 on a Buick is GM's "Fuel Level Sensor 1 Circuit High Voltage": the signal from the fuel tank's level sender has gone above the range a working sender can produce. It usually shows up with a fuel gauge stuck on empty, a low-fuel warning that won't go away, or a gauge that drops and recovers. The cause is often not the sender itself. GM has documented a corroded connector behind the right rear wheel liner on 2010–2012 LaCrosse and 2011–2012 Regal, a blocked fuel pump jet on the 2018 Enclave AWD that GM says to fix with the pump, not the sender, and a fuel level sensor special coverage on the 2005–2007 Rainier.

What Does P0463 Mean on a Buick?

Inside the fuel tank, a float on an arm rides the fuel surface and moves a wiper across a resistor — the fuel level sensor, or sender. The engine control module (ECM) reads it as a voltage and shares the result with the instrument cluster for the gauge and the range display. GM also uses fuel level to decide when EVAP leak tests can run.

GM's 2019 diagnostic table for the Buick engine group (Encore, Cascada, Regal, LaCrosse and Enclave) describes P0463 as detecting a primary fuel tank level sensor stuck out of range high. It must fail 100 of 125 samples to count, and it is a Type B, two-trip code — so a single glitch won't turn the light on, but a fault that stays will.

"Sensor 1" is the primary sender. Buicks with a two-chamber "saddle" tank — the AWD Enclave is one — also have a second sender, whose matching code is P2068.

How the Fuel Level Signal Works

GM's bulletin 18-NA-365 for the 2017–2018 GM three-row crossovers gives the useful number: on those tanks both fuel level sensors sweep from about 40 to 250 ohms, and when both read 250 ohms the tank is empty. In other words, on that system higher resistance means less fuel.

That explains the pattern behind P0463. If the sender's track wears through, a wire breaks, or a connector corrodes open, the resistance the ECM sees goes far past "empty," and the signal voltage rises above anything a working sender can produce. The ECM flags it as "circuit high." So when P0463 sets, the gauge typically drops to empty or below — even with a full tank.

The practical lesson: P0463 is an open-circuit style fault until proven otherwise. Wiring and connectors deserve as much attention as the sender in the tank — and they're far easier to reach.

Which Buicks Set P0463

We searched GM's OBD tables from 1997 through 2025. P0463 appears for Buick engine groups from the 2000 tables onward — the 3800, 3.1L and 3.4L Buicks, the LaCrosse, Allure, Lucerne, Terraza, Rendezvous and Rainier, and every 2010-and-later Buick, including the Regal, Verano, Encore, Cascada, Envision, Enclave, Encore GX and Envista. The 1997 3800 tables we checked did not include it.

What GM's Buick Documents Say

2018 Enclave AWD — it may be the pump, not the sender (18-NA-365, February 2019). This bulletin covers the Enclave, Traverse, Acadia and Cadillac XT5 with the 3.6L LFY or LGX and all-wheel drive, in a 2017–2018 range; for Buick that means the redesigned 2018 Enclave. Owners may report stalling, lack of performance, or a low range reading while the gauge shows adequate fuel, with codes including P0461–P0464, P2066–P2068, P018B and P2635. GM's cause: a partially or fully blocked transfer jet port in the primary fuel pump module. AWD tanks have two sides, and that jet is what pulls fuel across from the secondary side. When it's blocked, fuel strands on one side and the two level readings stop making sense.

GM's procedure checks both fuel level sensor resistances at connector X350 (chassis harness to fuel tank harness), confirms the primary sensor sweeps freely, then uses a measured gallon of fuel to see whether transfer is happening. GM is explicit: if the primary pump is the cause, replace only the pump, not the fuel level sending sensor.

2010–2012 LaCrosse and 2011–2012 Regal — corroded connector (PIC5327C, May 2012). An intermittent service engine soon light traced to corrosion at connector X403 on the LaCrosse or X350 on the Regal. GM's fix is to remove the right rear wheel well liner, inspect the connector, repair or replace it, and pack it with dielectric grease. GM's code list for this bulletin includes P0461, P0462, P0463 and P0464 alongside EVAP vent, tank pressure and fuel pressure codes — a strong clue when several of them appear together.

2005–2007 Rainier — Special Coverage 10054 (August 2011). GM found that the contacts on the fuel level sensor in the Rainier (and TrailBlazer and Envoy) could wear prematurely. GM describes the gauge reading empty after filling the tank with the check engine light on; as fuel drops the light may go out and the gauge may read slightly high, until eventually it stops working altogether. The bulletin doesn't name a DTC, so we can't confirm which fuel level code it sets. Coverage was 10 years or 120,000 miles, with GM paying 50% of a new-design sensor (GM lists sensor kit 19178477 for the Rainier). That term has passed for practical purposes, though a dealer VIN check is free.

Buick Gauge Problems That Don't Set P0463

Not every Buick fuel gauge complaint is P0463. GM has published several Buick gauge documents that name no code at all, and they need a different fix:

• 2013–2015 LaCrosse and Regal (FWD) — gauge stops at 7/8 (PI1401A, February 2015). Build variation in the fuel level sensor; GM released a new sensor kit, 13594132, and says not to replace the fuel shutoff valve.
• 2012 LaCrosse and Regal built before January 1, 2012 — gauge reads low or responds slowly after a fill (PI0658, January 2012). A misshapen sender housing can hinder the float arm; GM's procedure is to remove and inspect the sensor.
• 2021–2023 Enclave, Encore GX, Envision, LaCrosse and Regal — erratic or dead gauge with stalling (24-NA-139, July 2024). That one sets P023F and/or P129F and traces to the fuel pump driver control module, not the sender.

If your gauge misbehaves but P0463 isn't stored, one of these may fit better.

Symptoms of P0463

• Check engine light
• Fuel gauge reading empty — or below empty — with fuel in the tank
• Low fuel warning, chime or message that won't clear
• Range (miles to empty) display that makes no sense
• A gauge that drops out and recovers over bumps or in wet weather (intermittent wiring)
• Other fuel level codes (P0461, P0462, P0464, P2066–P2068) and, on a 2010–2012 LaCrosse or 2011–2012 Regal, EVAP codes too
• On a 2018 Enclave AWD, stalling or lack of performance with a low range reading (18-NA-365)

Causes and How to Confirm Each

How Is P0463 Diagnosed on a Buick?

1. Read every code with GM descriptions. A cluster of fuel level, EVAP and tank pressure codes points at a shared connector; P0463 with P2068 or P2635 on an AWD Enclave points toward fuel transfer.
2. Check your VIN for open bulletins and coverages.
3. Watch the fuel level reading on a scan tool. A value pinned at the limit suggests an open circuit; one that jumps around suggests a worn track or an intermittent connector.
4. On a 2010–2012 LaCrosse or 2011–2012 Regal, inspect connector X403/X350 behind the right rear wheel well liner, per PIC5327C.
5. Measure sender resistance at the tank harness connector. On the GM crossovers in 18-NA-365 the normal sweep is about 40–250 ohms; an open reading means a break in the sender or its wiring.
6. Check the circuits back to the ECM for continuity and shorts.
7. On a 2018 Enclave AWD, follow 18-NA-365 — check both senders and fuel transfer before condemning a sender.
8. Replace the sender only when it tests bad, and order by VIN.
9. Clear the code and confirm the gauge tracks a fill-up. P0463 is a two-trip code, so give it a couple of drives.

Parts and Cost

GM Documents Relevant to P0463 on a Buick

Have a dealer check your VIN against current bulletins and campaigns rather than relying on any article, including this one.

What Other P0463 Pages Get Wrong

• "Replace the fuel level sender." GM's Buick documents point at a corroded connector on the LaCrosse and Regal and at the fuel pump on the 2018 Enclave AWD — where GM says not to replace the sender.
• Dropping the tank before checking the wiring. A resistance check at the tank connector tells you whether the problem is inside the tank at all.
• Treating every gauge complaint as P0463. GM's 7/8-full and slow-gauge bulletins for the LaCrosse and Regal set no code, and the 2021–2023 gauge problem uses P023F/P129F.
• Ignoring the second sender. AWD saddle tanks have two; P2066–P2068 are the second sender's codes.
• Expecting the light from a single glitch. GM makes P0463 a two-trip code.

Frequently Asked Questions

Is P0463 serious?

The code itself won't hurt the engine, but a gauge you can't trust can leave you out of fuel. On a 2018 Enclave AWD, GM links these codes to stalling from stranded fuel, so get that checked promptly.

My Buick's gauge says empty after I filled it. Is that P0463?

That is the classic P0463 pattern, because an open sender or wire reads as far past empty. On a 2005–2007 Rainier it is also exactly what GM described in Special Coverage 10054.

Do I have to drop the tank to fix P0463?

Not always. Check the connectors and measure the sender's resistance at the tank harness first. If the reading is good there, the problem is in the wiring or a connector outside the tank.

Why does my LaCrosse have P0463 plus EVAP codes?

GM's PIC5327C describes corrosion at connector X403 (LaCrosse) or X350 (Regal) behind the right rear wheel well liner on 2010–2012 LaCrosse and 2011–2012 Regal, setting fuel level and EVAP codes together. Repair the connector first.

Is the Rainier fuel level sensor coverage still active?

Special Coverage 10054 ran 10 years or 120,000 miles from the original in-service date, with GM paying half. For 2005–2007 Rainiers that term has passed for practical purposes. A dealer VIN check is still free.

My 2018 Enclave stalls with fuel level codes. What's going on?

GM's 18-NA-365 traces that to a blocked transfer jet in the primary fuel pump module on AWD models, which strands fuel on one side of the tank. GM's fix is the pump, not the fuel level sender.

Can a bad ground cause P0463?

Yes. A poor ground or corroded connector adds resistance, and on this circuit extra resistance looks like less fuel — or an open. Check grounds and connectors before parts.