AutoCodes – Audi – P0599 Audi

P0599 Audi Code - Thermostat Heater Control Circuit High

Quick Answer

The Engine Control Module (ECM) controls the Pulse Width Modulated (PWM) thermostat. Common causes include Failed Engine Cooling Thermostat, Engine Cooling Thermostat harness is open or shorted, Engine Cooling Thermostat 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 Audi indicates Thermostat Heater Control Circuit High.
Common causes: Common causes include Failed Engine Cooling Thermostat, Engine Cooling Thermostat harness is open or shorted, Engine Cooling Thermostat 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 11,259

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 Audi Description

The Engine Control Module (ECM) controls the Pulse Width Modulated (PWM) thermostat. The engine coolant thermostat heater controls coolant flow and regulates the engine operating temperature. The ECM supplies 12 V to the thermostat. The ECM controls the engine coolant thermostat heater by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

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

What does this mean?

What are the Possible Causes of the DTC P0599 Audi?

Failed Engine Cooling Thermostat
Engine Cooling Thermostat harness is open or shorted
Engine Cooling Thermostat circuit poor electrical connection

How to Fix the DTC P0599 Audi?

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

If there are no coolant system leaks, replace the thermostat to fix the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0599 Audi 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.

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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 Audi Code

1. What does the OBDII code P0599 mean on an Audi?

P0599 indicates a high voltage issue in the thermostat heater control circuit, which is responsible for regulating the engine's operating temperature.

2. What are the symptoms of a P0599 code on an Audi?

Symptoms may include an illuminated check engine light, poor fuel efficiency, engine overheating, or the engine taking too long to reach operating temperature.

3. What causes the P0599 code on an Audi?

Common causes include a faulty thermostat heater, damaged wiring or connectors in the thermostat control circuit, a failed coolant temperature sensor, or a malfunctioning engine control module (ECM).

4. Can I drive my Audi with a P0599 code?

While the vehicle may still run, driving with this code can lead to engine overheating or inefficient engine performance, potentially causing further damage over time.

5. How is the P0599 code diagnosed on an Audi?

A mechanic will typically use an OBDII scanner to confirm the code, inspect the thermostat heater and wiring, and test the voltage and resistance of the thermostat control circuit.

6. How do you fix a P0599 code on an Audi?

Repairs may involve replacing the thermostat assembly, repairing damaged wiring or connectors, or in rare cases, replacing the ECM.

7. How much does it cost to fix a P0599 code on an Audi?

The cost varies depending on the issue, but replacing the thermostat typically costs between $200 and $500, including parts and labor.

8. Can a P0599 code be caused by low coolant levels?

Low coolant levels are unlikely to directly cause this code but can lead to overheating, which may indirectly affect the thermostatâ€™s operation.

9. Does clearing the P0599 code fix the problem?

Clearing the code will temporarily turn off the check engine light, but the underlying issue must be addressed to prevent the code from returning.

10. How can I prevent the P0599 code from occurring again?

Regular maintenance, including checking coolant levels and inspecting wiring for damage, can help prevent issues with the thermostat heater control circuit.