P2556 code meaning
Engine Coolant Level Sensor/Switch Circuit
What P2556 means
P2556 is the general circuit code for the coolant level sensor or switch, normally fitted in the expansion tank. Deutz uses it on its EMR L1 engine control for industrial engines with the sub-code P2556-F0, a ground error, under SPN 111. Mercedes-Benz goes its own way and stores P2556-7B, meaning the sensor reports a fluid level that is too low. Bulletin LI20.30-P-078333 (August 2024) covers the EQB, where this code lands in the signal acquisition module SAM N10: air pushed into the circuit by the electric drive forms a cushion in the tank, so the level drops below the warning mark while driving; a red cap, filling 20 mm over max and if needed a revised tank fix it. LI09.41-N-079165 for OM654 Sprinter vans links the same code to coolant lost through an intercooler that leaks internally. P2560 is the plain low-level code.
P2556 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2556
- Low coolant warning in the cluster
- Coolant level appears correct after opening the cap
Common causes of P2556
- Most likelyDamaged wiring or ground at the level sensor
- PossibleAir cushion in the expansion tank (Mercedes EQB)
- PossibleReal coolant loss, e.g. internal charge air cooler leak
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Coolant level sensorSensor wiring
What each part of P2556 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| 56 | The exact fault in that area. |
What to do next
- Note P2556 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 P2556
What does P2556 mean?
P2556 means "Engine Coolant Level Sensor/Switch Circuit". P2556 is the general circuit code for the coolant level sensor or switch, normally fitted in the expansion tank. It is a generic code, so it means the same on every make.
Is it safe to drive with P2556?
P2556 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P2556 fail an emissions test?
P2556 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P2556 to fix?
Difficulty: medium. A typical repair takes 0.3 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2556 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.