P0463 means the fuel level sender is reporting a level the engine computer does not believe, usually higher than the tank actually holds. It is a gauge problem rather than an engine problem, so it is more annoyance than danger. Usually OK to drive, get it checked soon. Indicative UK repair cost is £60 to £350.
The sender is a float on an arm inside the tank, connected to a variable resistor. As fuel is used the float drops, the resistance changes, and the gauge follows it. When the computer sees a value outside the range that float could physically produce, it stores this code. Nothing about how the engine runs depends on that reading, which is why this is the least mechanically serious fault in this library. It is not, however, completely without consequences, and the two that matter are worth knowing before you dismiss it.
Can I drive with P0463?
Usually OK to drive, get it checked soon. The engine does not care. You should, for two specific reasons.
The first is obvious once said: a gauge reading higher than the truth means you can run out of fuel while believing you have a quarter of a tank. On a petrol car that is a recovery truck and an embarrassing afternoon. On a diesel it can be worse, because running a modern diesel dry can mean the fuel system needs bleeding properly before it will start again, and some will not self-prime.
The second is less obvious and applies to diesels with a particulate filter. A great many cars refuse to begin a filter regeneration below roughly a quarter of a tank. If your sender is reading high, the car may believe it has plenty when it does not, and quietly stop regenerating. Weeks of that produces a filter problem that costs a great deal more than a sender unit, and nobody connects the two faults because they look unrelated.
What P0463 means for your MOT
The fuel gauge is not an MOT item. There is nothing in the inspection manual about whether your dashboard tells you the truth about the tank, and no tester will check it.
The fuel system items that do exist, in section 6.1.3 of the DVSA MOT inspection manual, are about leaks, security and the filler cap, not about measurement. So this code's only route to a failure is the engine management lamp, if your car lights it at all for this fault, which varies between manufacturers. Where it does, that is a major defect under section 8.2.1.2 for petrol cars first used on or after 1 July 2003, and 8.2.2.2 for diesels first used on or after 1 July 2008.
One practical note rather than a regulatory one: the emissions test needs the engine running, and a diesel smoke test needs it revved up repeatedly. Arriving for an MOT with a tank you believed was half full and is actually nearly empty is a self-inflicted problem, and it is a real one with this code.
What usually causes it
- A faulty sender unit. The resistive track inside wears where the wiper sits, and because cars spend most of their lives in the middle of the tank's range, that is where the track wears first. A gauge that behaves at full and empty but misreads in between is this.
- A wiring fault. The sender's wiring passes through the top of the tank, which means a connector in an awkward, sometimes damp place. Corrosion there or a chafed wire produces an out-of-range reading identical to a dead sender.
- A stuck float. The arm can foul on something inside the tank, or the float itself can take on fuel and stop floating. A gauge that sits at one value and never moves at all, rather than reading erratically, points here.
Worth adding for anyone with a larger car: some vehicles have a saddle-shaped tank with two senders in it, one each side. When only one has failed, the gauge behaves normally over part of its range and then sticks or jumps, which is confusing until you know there are two.
What it costs to fix in the UK
£60 to £350. A wiring or connector repair at the top of the tank is the bottom. A sender unit on a car with an access panel under the rear seat is the middle. The top is a car where the tank has to be dropped to reach the sender, where the labour is most of the bill, and a vehicle with two senders can go beyond it if both are replaced.
Given that the repair can cost more than the inconvenience justifies, plenty of owners choose to live with it and track mileage instead. That is a legitimate choice as long as the lamp is not an MOT problem and the diesel filter issue above does not apply to your car. What a car diagnostic costs in the UK helps you price the alternative.
These are indicative UK ranges for guidance only. Actual causes and prices vary by vehicle, and a stored code points to a system, not always the exact part.
What to check first
- Measure the error rather than describing it. Fill the tank completely, note the gauge, then record the miles covered and the litres taken at the next fill. That tells you how wrong the gauge is and in which direction, which is information no code reader gives you and which decides whether this is worth fixing.
- Watch the gauge across a full tank. A reading that moves normally at the top and then sticks halfway behaves differently from one that never moves at all, and on a car with two senders that pattern points at which one has gone.
- Check the connector at the top of the tank. On many cars this is reachable under the rear seat or through a boot panel without dropping anything. Corrosion or a loose plug there is the cheap outcome.
- If it is a diesel with a particulate filter, read the soot load too. Not because it is related electrically, but because the filter may have been quietly failing to regenerate for weeks, and finding that now is a great deal cheaper than finding it later.
Related codes
- P2002, diesel particulate filter efficiency low. The expensive consequence described above, and the reason this harmless-looking code deserves a read of the filter data alongside it.
- P0562, system voltage low. The other electrical supply fault in this group, and worth ruling out when several unrelated sensors are reading implausibly.
- P0442, P0455 and P0456, EVAP system leaks. The other codes that live around the fuel tank, and the ones where the filler cap genuinely is an MOT item.
Get it narrowed down before you spend
A stored code tells you which system is unhappy, not which part has failed. If you want it narrowed down before you spend anything, send the code and your symptoms and a mechanic will read them personally. Quick Diagnosis is £20, and if we can't help, you don't pay.
Written by the First Diagnostic mechanic. Over a decade in the trade: a VW-only workshop running diagnostics and electrical repair, then BMW-only through to full engine rebuilds. Now an independent all-makes workshop, plus building and wiring drift cars for competition, including trackside work as head mechanic. More about who reads your codes.