AutoCodes – Mercedes-Benz – P0789 Mercedes-Benz

P0789 Mercedes-Benz Code - Shift/Timing Solenoid Intermittent

Quick Answer

Shift solenoid valve ST is switched ON OFF by a signal from Engine Control Module (ECM) so that let in or out timing of 2nd brake is adjusted by operating orifice control valve. Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty shifting solenoid valve. 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: P0789 Mercedes-Benz indicates Shift/Timing Solenoid Intermittent.
Common causes: Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty shifting solenoid valve.
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 2,970

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 08, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0789 Mercedes-Benz Description

Shift solenoid valve ST is switched ON OFF by a signal from Engine Control Module (ECM) so that let in or out timing of 2nd brake is adjusted by operating orifice control valve. Therefore, shift solenoid valve ST operates when letting in or out reverse clutch.

OBDII Code P0789 Mercedes-Benz - Shift/Timing Solenoid Intermittent - AutoCodes.com — P0789 Mercedes-Benz Code - Shift/Timing Solenoid Intermittent

What does this mean?

What are the Possible Causes of the DTC P0789 Mercedes-Benz?

Low transmission fluid level
Dirty transmission fluid
Faulty shifting solenoid valve
Shifting solenoid valve harness is open or shorted
Shifting solenoid valve circuit poor electrical connection

How to Fix the DTC P0789 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0789 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 P0789 Mercedes-Benz code?

Need more information on how to fix the P0789 Mercedes-Benz code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0789 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 P0789 Mercedes-Benz Code

1. What does the P0789 code mean for a Mercedes-Benz?

The P0789 code indicates an intermittent issue with the shift/timing solenoid, which can affect gear shifting and transmission performance.

2. What are the common symptoms of the P0789 code in a Mercedes-Benz?

Symptoms may include harsh or delayed shifting, slipping gears, reduced fuel efficiency, transmission warning lights, or the vehicle going into limp mode.

3. What causes the P0789 code to be triggered?

Common causes include a faulty shift/timing solenoid, low or dirty transmission fluid, damaged wiring or connectors, or a malfunctioning transmission control module (TCM).

4. Can I continue driving my Mercedes-Benz with the P0789 code?

Itâ€™s not recommended to drive for extended periods, as this code can lead to further transmission damage if left unaddressed.

5. How do I diagnose the P0789 code?

Diagnosis involves scanning for codes, inspecting the transmission fluid, checking solenoid operation, and examining wiring and connectors for damage or corrosion.

6. How is the P0789 code fixed on a Mercedes-Benz?

Repairs may include replacing the faulty solenoid, cleaning or replacing the transmission fluid, repairing damaged wiring, or reprogramming the TCM.

7. How much does it cost to fix the P0789 code on a Mercedes-Benz?

Repair costs can range from $150 to $500 or more, depending on whether the issue is related to the solenoid, wiring, or transmission control module.

8. Can low transmission fluid cause the P0789 code?

Yes, low or contaminated transmission fluid can lead to improper solenoid function and trigger the P0789 code.

9. Do I need to replace the entire transmission to fix the P0789 code?

In most cases, replacing the solenoid or addressing the specific fault will resolve the issue without requiring a full transmission replacement.

10. Can I fix the P0789 code myself?

If you're experienced with transmission systems, you may be able to replace the solenoid or repair wiring yourself, but professional diagnosis and repair are recommended for accurate results.