What Does P1599 Mean?
This code indicates the A/C pressure sensor is outputting a voltage below the expected minimum range. This may indicate a low refrigerant charge, a sensor fault, or a wiring issue creating a ground path on the signal wire. The PCM will likely disable the A/C compressor clutch to prevent damage from running the system without adequate refrigerant.
Common Causes
30%
Low refrigerant charge due to system leak
25%
Failed A/C pressure sensor reading falsely low
20%
Short to ground in the A/C pressure sensor signal wire
15%
Corroded A/C pressure sensor connector
10%
A/C system completely evacuated (empty)
Diagnostic Steps
1
Connect A/C manifold gauges to verify actual system pressures; if both high and low sides are near zero, the system has lost its charge.
2
If the system has adequate pressure but the sensor reads low, inspect the pressure sensor connector for corrosion, moisture, or damage.
3
Measure the sensor output voltage; with the system at ambient temperature and a normal charge, it should read above the minimum threshold per the service manual.
4
Check the signal wire for shorts to ground between the sensor and PCM.
5
If the system is low on refrigerant, perform a leak test using UV dye or electronic leak detector before recharging.
Estimated Repair Cost
$50 - $400
Parts + labor, varies by vehicle and location
This code indicates the A/C pressure sensor is outputting a voltage below the expected minimum range. This may indicate a low refrigerant charge, a sensor fault, or a wiring issue creating a ground path on the signal wire. The PCM will likely disable the A/C compressor clutch to prevent damage from ...
The most common cause of P1599 (A/C Pressure Sensor Volts Too Low) is: Low refrigerant charge due to system leak
Typical repair costs for P1599 range from $50 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
No direct driving safety concern. A/C will not function, causing discomfort in hot weather. Running a compressor with inadequate refrigerant can destroy the compressor due to lack of oil circulation.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1599 to identify the root cause.
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Quick Info
Category
Powertrain
System
Air Conditioning / HVAC
Difficulty
Type
Manufacturer
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