P0793 on Mercedes-Benz: How to Diagnose & Fix
Intermediate Shaft Speed Sensor "A" Circuit No Signal
1 Mercedes-Benz model · 1 documented issue · 1 critical · $900-$2,000 repair
P0793 on Mercedes-Benz by model: symptoms, diagnosis and fix
The 722.9 7G-Tronic automatic transmission used in later R171 models is known for conductor plate and internal speed sensor failures. When the plate or sensors fail, the transmission may enter limp mode, shift harshly, or get stuck in one gear due to loss of accurate input/output speed data.
Common Symptoms
- Transmission stuck in limp mode
- Harsh or delayed shifting
- Vehicle starts in second gear
- Transmission warning message
- Check engine light or transmission fault codes
How to Fix
Diagnosis involves scanning the transmission control module for speed sensor and gear ratio faults, then confirming fluid condition and connector integrity. Repair usually includes replacing the conductor plate, transmission connector sleeve, fluid, and filter, followed by adaptation reset and relearn. Typical repair cost is about $900-$2,000 at an independent Mercedes specialist.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mercedes 722.9 conductor-plate service kit 000270260080OEMMercedes-Benz A000270260080 / kit 000270260080KT
Matched 722.9 VGS/conductor-plate repair after EHS generation and internal speed-sensor failure are confirmed Fitment/availability: The inspected direct U.S.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- TipUse the correct Mercedes-spec transmission fluid and perform adaptation reset after repair.
P0793 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0793 mean on a Mercedes-Benz?
P0793 stands for "Intermediate Shaft Speed Sensor "A" Circuit No Signal." This code sets when the transmission control module receives no signal from the intermediate shaft speed sensor (sensor A). This sensor measures the rotational speed of an intermediate shaft inside the automatic transmission/transaxle, and the module uses it to calculate gear ratios and command proper shifts. Without this signal the transmission may shift harshly, shift erratically, or enter failsafe mode. The fault is usually in the sensor, its wiring, or the related circuit. On Mercedes-Benz it is documented across 1 model: SLK-Class.
What are the most common causes of P0793?
The most common causes of P0793 are: Failed intermediate shaft speed sensor, Damaged, corroded, or loose wiring/connector, Open or short in the sensor circuit, Metal debris on the sensor tip, Low or dirty transmission fluid affecting sensor reading, Internal transmission wiring fault, Faulty transmission control module (less common). The specific cause varies by vehicle.
How much does it cost to fix P0793 on a Mercedes-Benz?
Published repair estimates on Mercedes-Benz range from $900 to $2,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0793 on a different make?
View P0793 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.