P2C51 code meaning
Fuel Level Sensor A/B Correlation
Powertrain system Generic code P2Cxx codes Check engine light
What P2C51 means
Saddle tanks have two chambers and therefore two level senders, A and B; the engine module combines both resistances into one fuel level. GM's bulletin PI0926 for the 2011–2013 Equinox and Terrain shows this layout, with each sender reading about 40 Ω when full. P2C51 means the two senders disagree more than the tank design allows. A Hyundai patent describes such a check: it stores the voltage difference between both senders and starts its fault diagnosis when that difference stays the same although fuel has been used. No manufacturer publicly documents P2C51 itself; Ford and GM use P0461/P2066 and the stuck codes P25B0–P25B2 instead. CARB requires fuel level rationality because EVAP and misfire monitors rely on it.
P2C51 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor1 to 5 hours
- Clears after repairAfter a drive cycle
Symptoms of P2C51
- Fuel gauge inaccurate or not reading full after filling
- Check engine lamp
- Range display jumps
Common causes of P2C51
- Most likelyWorn resistor track or sticking float on one sender
- PossibleJet pump not transferring fuel between the tank halves
- PossibleCorroded connector adding resistance on one sender
- Less likelyWrong or misassembled sender after tank work
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel level sensor aFuel level sensor bECM
What each part of P2C51 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| C | Area: hybrid propulsion. |
| 51 | The exact fault in that area. |
What to do next
- Note P2C51 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2C51
What does P2C51 mean?
P2C51 means "Fuel Level Sensor A/B Correlation". Saddle tanks have two chambers and therefore two level senders, A and B; the engine module combines both resistances into one fuel level. It is a generic code, so it means the same on every make.
Is it safe to drive with P2C51?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2C51 fail an emissions test?
Yes, it can. P2C51 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2C51 to fix?
Difficulty: medium. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P2C51 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.