AutoCodes – Mercedes-Benz – P0599 Mercedes-Benz

P0599 Mercedes-Benz Code - Thermostat Heater Control Circuit High

Quick Answer

This fault code is stored in the Engine Control Module (ECM) when the thermostat heater control circuit malfunctions. Common causes include Faulty Thermostat Heater Control Relay, Thermostat Heater Control Relay harness is open or shorted, Thermostat Heater Control Relay 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: P0599 Mercedes-Benz indicates Thermostat Heater Control Circuit High.
Common causes: Common causes include Faulty Thermostat Heater Control Relay, Thermostat Heater Control Relay harness is open or shorted, Thermostat Heater Control Relay 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 7,963

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 May 27, 2024

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0599 Mercedes-Benz Description

This fault code is stored in the Engine Control Module (ECM) when the thermostat heater control circuit malfunctions. An electronically controlled heater element is integrated into the engine coolant thermostat. The purpose of the heater element is to allow the conventional wax thermostat to open at a lower coolant temperature. Greater cooling is required under full load conditions so the thermostat can be opened at a lower temperature to allow greater cooling. The thermostat operates in the conventional way during low or part load conditions. The thermostat heater element has a system voltage supply and a pulse width modulated ground control circuit.

OBDII Code P0599 Mercedes-Benz - Thermostat Heater Control Circuit High - AutoCodes.com — P0599 Mercedes-Benz Code - Thermostat Heater Control Circuit High

What does this mean?

What are the Possible Causes of the DTC P0599 Mercedes-Benz?

Faulty Thermostat Heater Control Relay
Thermostat Heater Control Relay harness is open or shorted
Thermostat Heater Control Relay circuit poor electrical connection

How to Fix the DTC P0599 Mercedes-Benz?

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 does this mean?

Code Tech Notes

Mercedes Benz Code = 0153 (Three-disk thermostat valve) has a short circuit to positive. (P0599)

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0599 Mercedes-Benz 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 P0599 Mercedes-Benz code?

Need more information on how to fix the P0599 Mercedes-Benz code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0599 Mercedes-Benz 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 P0599 Mercedes-Benz Code

1. What are the common symptoms of OBDII code P0599 in a Mercedes-Benz related to the thermostat heater control circuit high?

- Common symptoms include engine overheating, slow engine warm-up, poor fuel economy, and potential illumination of the Check Engine Light.

2. What are the possible causes of OBDII code P0599 in a Mercedes-Benz?

- The code P0599 is typically caused by a malfunction in the thermostat heater control circuit due to a faulty thermostat, damaged wiring, or a failed thermostat heater.

3. How can I diagnose OBDII code P0599 in my Mercedes-Benz?

- Diagnosing code P0599 usually involves checking the thermostat and its connections, testing the thermostat heater circuit for continuity, and using a scan tool to retrieve fault codes and data.

4. Can I continue driving my Mercedes-Benz with OBDII code P0599 present?

- It is not recommended to drive your vehicle with code P0599 as it can lead to engine overheating and potential damage. It is advised to address the issue promptly.

5. Is it possible to reset the OBDII code P0599 in a Mercedes-Benz without fixing the underlying issue?

- Resetting the code without fixing the root cause will only temporarily turn off the Check Engine Light. The issue will likely reoccur until the thermostat heater control circuit problem is resolved.

6. How can I repair OBDII code P0599 in my Mercedes-Benz?

- Repairing code P0599 involves replacing a faulty thermostat, repairing damaged wiring, or replacing the thermostat heater, depending on the specific cause of the issue.

7. Are there any tips to prevent OBDII code P0599 from occurring in my Mercedes-Benz?

- Regular maintenance, including checking the thermostat and its connections, can help prevent code P0599. Promptly addressing any cooling system issues can also prevent this code from appearing.

8. Can a DIY enthusiast fix OBDII code P0599 in a Mercedes-Benz?

- Depending on their skill level and access to tools, a DIY enthusiast may be able to diagnose and repair code P0599. However, it is recommended to consult a professional technician for proper diagnosis and repair.

9. How long does it typically take to repair OBDII code P0599 in a Mercedes-Benz?

- The repair time for code P0599 can vary depending on the cause of the issue and the extent of repairs needed. It can take anywhere from a few hours to a full day to complete the repair.

10. Will fixing OBDII code P0599 improve the performance and fuel efficiency of my Mercedes-Benz?

- Yes, resolving code P0599 can lead to improved engine performance, better fuel efficiency, and proper engine temperature regulation in your Mercedes-Benz.