AutoCodes – Generic – B1859

B1859 Code - Climate Control A/C Pressure Switch Circuit Open

Quick Answer

The Body Control Module (BCM) monitors the Climate Control A/C Pressure Switch. Common causes include Faulty Climate Control A/C Pressure Switch, Climate Control A/C Pressure Switch harness is open or shorted, Climate Control A/C Pressure Switch circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: B1859 indicates Climate Control A/C Pressure Switch Circuit Open.
Common causes: Common causes include Faulty Climate Control A/C Pressure Switch, Climate Control A/C Pressure Switch harness is open or shorted, Climate Control A/C Pressure Switch circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 4,702

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 07, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B1859 Description

The Body Control Module (BCM) monitors the Climate Control A/C Pressure Switch. The BCM sets the OBDII code when the Climate Control A/C Pressure Switch is not to factory specifications.

OBDII Code B1859 - Climate Control A/C Pressure Switch Circuit Open - AutoCodes.com — B1859 Code - Climate Control A/C Pressure Switch Circuit Open

What does this mean?

What are the Possible Causes of the DTC B1859?

Faulty Climate Control A/C Pressure Switch
Climate Control A/C Pressure Switch harness is open or shorted
Climate Control A/C Pressure Switch circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B1859?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B1859 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the B1859 code?

Need more information on how to fix the B1859 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B1859 code diagnosed by a professional: Find a repair shop in your area

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about B1859 Code

What does the OBDII code B1859 mean?

B1859 indicates that there is an open circuit in the climate control A/C pressure switch, which can affect the air conditioning system's operation.

What are common symptoms of the B1859 code?

Common symptoms include the air conditioning not functioning, erratic temperature control, and illumination of the check engine light.

What could cause the B1859 code to trigger?

Possible causes include a faulty A/C pressure switch, damaged wiring or connectors, low refrigerant levels, or issues with the climate control module.

How can I diagnose the B1859 code?

To diagnose B1859, check the A/C pressure switch for proper function, inspect wiring and connectors for damage, test refrigerant levels, and scan the vehicle's computer for additional codes.

What should I check first if I receive the B1859 code?

Start by inspecting the A/C pressure switch and its electrical connections for any signs of damage or corrosion.

Can low refrigerant levels trigger the B1859 code?

Yes, low refrigerant levels can cause the A/C pressure switch to report an open circuit, which may trigger the B1859 code.

What repairs are typically needed to fix the B1859 code?

Repairs may include replacing the A/C pressure switch, repairing or replacing damaged wiring, or recharging the A/C system with refrigerant.

Is it safe to drive a car with the B1859 code?

While it may be safe to drive, the A/C system will not function properly, and it's advisable to address the issue to ensure comfort and prevent further damage.

How can I prevent the B1859 code from recurring?

Regular maintenance of the A/C system, including checking refrigerant levels and inspecting electrical components, can help prevent the recurrence of the B1859 code.