P0722: How to Diagnose & Fix — Output Speed Sensor Circuit No Signal
6 vehicles · 4 makes · $150-$3,500 repair
How to diagnose and fix P0722: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Mercedes-Benz E-Class · 2004–2012
The 722.9 7G-Tronic transmission conductor plate (internal electrical board with speed sensors) fails, causing limp mode, harsh shifting, and loss of gears. The electrical connector corrodes or the sensors crack from heat cycling.
Common Symptoms
- Transmission goes into limp mode (stuck in one gear)
- Harsh shifting between gears
How to Fix
Replace the conductor plate and both speed sensors inside the transmission. Requires dropping the transmission pan and valve body. Replace the transmission filter and fluid at the same time.
Owner tips & cautions
- TipThe conductor plate is a $150 part and 3-hour DIY job. Many shops quote $1,500+ because they don't differentiate it from a full valve body replacement.
Sources for this issue (4)
- ECU Testing: Mercedes 7G-Tronic TCM conductor plate failuremanufacturer
- MB Medic: 722.9 7G-Tronic Valve Body & Conductor Plate Must Readmedia
- UpFix: 722.9 Transmission Conductor Plate Repair Could Save $1000smanufacturer
- The Autopian: Heres What A Conductor Plate Is And Why It Kills So Many Mercedes Vehiclesmedia
Mercedes-Benz C-Class · 2006–2013
The 722.9 7G-Tronic automatic transmission develops valve body issues causing harsh or delayed shifts, particularly the 2-3 and 4-5 upshifts. The conductor plate (electrical connector inside the valve body) is also failure-prone.
Common Symptoms
- Harsh or jerky shifting
- Delayed engagement when shifting from P to D
How to Fix
Replace the valve body or have it rebuilt by a Mercedes transmission specialist. Replace the conductor plate and speed sensors at the same time. A full transmission fluid and filter service may temporarily improve symptoms.
Owner tips & cautions
- TipChange the transmission fluid and filter every 40,000 miles. Mercedes calls it a "lifetime fill" but regular service dramatically extends valve body life.
Sources for this issue (6)
- MB Medic: 722.9 7G-Tronic Valve Body & Conductor Plate Must Readmedia
- CarComplaints: Mercedes 722.9 7G-Tronic Transmission Problems Cause Lawsuitother
- UpFix: 722.9 Transmission Conductor Plate Repair Could Save $1000smanufacturer
- MB Medic: 722.9 7G Tronic Automatic Transmission Problems and Solutionsmedia
- ECU Testing: Mercedes 7G-Tronic TCM conductor plate failuremanufacturer
- Transmission Repair Cost Guide: 722.9 Valve Body Problems & Solutionsmedia
Mercedes-Benz SLK/SLC · 2005–2011
The electronic conductor plate integrated into the 722.9 7-speed automatic's valve body (which houses the internal TCM, speed sensors and shift solenoids) is a widely reported failure on R171 SLKs equipped with the 7G-Tronic. As the plate's internal speed sensors and soldered joints degrade with heat cycling, the transmission drops into limp mode, typically locking into a single forward gear (often 2nd). The condition is temperature-sensitive and commonly appears from roughly 50,000-90,000 miles.
Common Symptoms
- Transmission stuck in gear (often 2nd), won't shift up
- Limp mode / reduced speed limited to ~40 mph
- Harsh or delayed shifts, especially when cold
- Intermittent faults that come and go with temperature
- Speed-sensor fault codes
How to Fix
Replace or rebuild the conductor plate (the revised design), refresh the valve body, and perform a transmission fluid and filter service plus an adaptation reset. Independent specialists offer a cheaper conductor-plate reman as an alternative to Mercedes' full valve-body replacement (roughly $2,000-$3,000 at a dealer). A neglected fluid service accelerates the failure, so periodic 722.9 fluid changes are recommended.
Sources for this issue (3)
Hyundai Elantra · 2001–2006
Ford F-150 · 2011–2020
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P0722 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 P0722 mean?
P0722 stands for "Output Speed Sensor Circuit No Signal." This code means the transmission control module is receiving no signal at all from the output speed sensor, which measures how fast the transmission's output shaft (and therefore the vehicle) is turning. The computer relies on this sensor to time gear shifts, control the torque converter, and confirm road speed, so when the signal drops out it suspects a broken circuit or dead sensor. You may notice harsh or erratic shifting, the transmission staying in one gear, or an inaccurate or dead speedometer. It is an electrical/no-signal fault rather than just an out-of-range reading.
What are the most common causes of P0722?
The most common causes of P0722 are: Failed output (vehicle) speed sensor, Broken, corroded, or loose sensor wiring or connector, Open or shorted circuit between sensor and TCM, Damaged sensor reluctor/tone ring on the output shaft, Metal debris or contamination on the sensor tip, Poor ground or power supply to the sensor, Faulty transmission control module (less common). The specific cause varies by vehicle.
How much does it cost to fix P0722?
Repair costs for P0722 range from $150 to $3,500, depending on the vehicle and root cause.
Which vehicles are affected by P0722?
Au7o has documented P0722 across 6 vehicle models from 4 manufacturers: Ford, GMC, Hyundai, Mercedes-Benz.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.