AutoCodes – Generic – C1740

C1740 Code - Left Rear Height Control Solenoid Valve Circuit

Quick Answer

The Suspension Electronic Control Unit (ECU) energizes the height control solenoid valve, which opens the valve and leads compressed air to the pneumatic cylinder, thus raising the vehicle height. Common causes include Faulty Left Rear Height Control Solenoid Valve, Left Rear Height Control Solenoid Valve harness is open or shorted, Left Rear Height Control Solenoid Valve 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: C1740 indicates Left Rear Height Control Solenoid Valve Circuit.
Common causes: Common causes include Faulty Left Rear Height Control Solenoid Valve, Left Rear Height Control Solenoid Valve harness is open or shorted, Left Rear Height Control Solenoid Valve 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 5,089

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 Nov 19, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C1740 Description

The Suspension Electronic Control Unit (ECU) energizes the height control solenoid valve, which opens the valve and leads compressed air to the pneumatic cylinder, thus raising the vehicle height. When the vehicle height is lowered, the ECU energizes not only the height control solenoid valve but also the exhaust valve which open the valve and discharge the compressed air in the pneumatic cylinder to the atmosphere. Front and rear height control valves have 2 solenoid valves to control right hand and left hand pneumatic cylinders separately. The exhaust valve is located on the compressor unit, and has one valve only.

OBDII Code C1740 - Left Rear Height Control Solenoid Valve Circuit - AutoCodes.com — C1740 Code - Left Rear Height Control Solenoid Valve Circuit

What does this mean?

What are the Possible Causes of the DTC C1740?

Faulty Left Rear Height Control Solenoid Valve
Left Rear Height Control Solenoid Valve harness is open or shorted
Left Rear Height Control Solenoid Valve circuit poor electrical connection
Faulty Suspension Electronic Control Unit (ECU)

How to Fix the DTC C1740?

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 C1740 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 C1740 code?

Need more information on how to fix the C1740 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the C1740 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

C1740 Lexus — Left Rear Height Control Solenoid Valve Circuit
C1740 Toyota — Left Rear Height Control Solenoid Valve Circuit

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 C1740 Code

1. What are the common symptoms of OBDII code C1740 (Left Rear Height Control Solenoid Valve Circuit)?

- Common symptoms include uneven ride height, sagging suspension on the left rear side of the vehicle, and potential issues with the vehicle's handling and stability.

2. What can cause OBDII code C1740 to trigger?

- The code C1740 can be triggered by a faulty left rear height control solenoid valve, damaged wiring or connectors in the circuit, or a malfunction in the vehicle's suspension system.

3. How can I diagnose the cause of OBDII code C1740?

- Diagnosis involves visually inspecting the left rear height control solenoid valve, checking the wiring and connectors for damage, and using a diagnostic scanner to retrieve live data from the suspension system.

4. What are the possible repair options for OBDII code C1740?

- Repair options may include replacing the left rear height control solenoid valve, repairing or replacing damaged wiring or connectors, and resetting the fault code using a diagnostic scanner.

5. Can I drive my vehicle with OBDII code C1740 present?

- It is not recommended to drive the vehicle with OBDII code C1740 present, as it can lead to further suspension issues and affect the vehicle's safety and performance.

6. How much does it cost to repair OBDII code C1740?

- The cost of repair can vary depending on the underlying cause of the code, but it may involve parts and labor costs ranging from $100 to $500 or more.

7. Is OBDII code C1740 a common issue in certain vehicle makes and models?

- OBDII code C1740 may be more common in vehicles equipped with air suspension systems, such as certain luxury brands or SUVs.

8. Can I reset OBDII code C1740 without fixing the underlying issue?

- While you can reset the fault code temporarily using a diagnostic scanner, it is recommended to address the root cause of the issue to prevent further suspension problems.

9. What steps can I take to prevent OBDII code C1740 from recurring?

- Regularly inspecting and maintaining the vehicle's suspension system, checking for any signs of wear or damage, and addressing issues promptly can help prevent OBDII code C1740 from recurring.

10. Do I need a professional mechanic to repair OBDII code C1740?

- While some DIY enthusiasts may be able to address the issue, it is recommended to consult a professional mechanic for proper diagnosis and repair of OBDII code C1740 to ensure the problem is resolved correctly.