P2518 code meaning
A/C Refrigerant Pressure Sensor B Circuit High
Powertrain system Generic code P25xx codes Check engine light
What P2518 means
P2518 is stored when pressure sensor B reports a signal close to its supply voltage. GM, which uses B for the low-side sensor in its hybrid tables, sets the limit at 98 % of the reference, about 4.90 V. Interesting is how the rating changed: the 2011 edition counted 40 of 50 samples and treated it as type B with two trips, while the 2016 and 2019 editions make it type A, lighting the lamp after a single failed drive; 2019 needs 4 s out of a 5 s window. Typical causes are a signal conductor shorted to 5 V or battery voltage, an open sensor ground, or water in the connector. A real pressure peak normally stays inside the range and does not trigger it. Compare P2517 for the low extreme and P2516 for a frozen but valid value.
P2518 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2518
- Check engine light after one drive on newer GM hybrids
- A/C compressor disabled, no cooling
Common causes of P2518
- Most likelySignal wire shorted to 5 V or battery voltage
- PossibleSensor ground open
- Less likelyMoisture or corrosion in the sensor connector
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Ac pressure sensor bSensor wiring
What each part of P2518 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. |
| 18 | The exact fault in that area. |
What to do next
- Note P2518 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 P2518
What does P2518 mean?
P2518 means "A/C Refrigerant Pressure Sensor B Circuit High". P2518 is stored when pressure sensor B reports a signal close to its supply voltage. It is a generic code, so it means the same on every make.
Is it safe to drive with P2518?
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 P2518 fail an emissions test?
Yes, it can. P2518 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 P2518 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. This is a job for a workshop.
Will P2518 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.