P0720: Output Speed Sensor Circuit Malfunction
Quick Answer
Not safe to drive
P0720 means the transmission control module is not receiving a proper signal from the output speed sensor. This sensor measures how fast the transmission output shaft rotates, which determines vehicle speed and helps the TCM calculate gear ratios and shift points.
- Severity
- High · Transmission
- Estimated repair cost
- From €85 to €350+, varies by vehicle
Scan your own car in about 60 seconds: see whether P0720 is really what it has, how urgent it is, and what the fix should cost. Free on iPhone and Android with an ELM327 adapter (Bluetooth LE on iPhone).
Get Skanyx freeWhat does P0720 mean?
P0720 is a transmission-related diagnostic trouble code classified as high severity. When your vehicle's ECU detects this condition, it stores P0720 and illuminates the check engine light.
What are the symptoms of P0720?
If your vehicle has triggered P0720, you may notice one or more of these symptoms:
- Check engine light and transmission warning light on
- Speedometer not working or reading incorrectly
- Harsh or delayed gear shifts
- Transmission stuck in limp mode
- ABS or traction control warning lights on
- Cruise control disabled
What causes P0720?
Here are the most common causes of P0720:
Faulty output speed sensor
: high
Damaged or corroded sensor wiring
: medium
Contaminated or low transmission fluid
: medium
Damaged tone ring/reluctor on output shaft
: low
TCM fault
: low
Is it safe to drive with P0720?
No - address this immediately. Without a valid output speed signal, the transmission cannot manage shift timing and the speedometer may read incorrectly. This affects ABS and stability control systems as well. Drive only to a garage.
How do you diagnose P0720?
Follow these steps to pinpoint the root cause of P0720:
- Check if the speedometer is working. A dead speedometer alongside P0720 strongly points to the output speed sensor, since both the transmission and instrument cluster rely on this signal.
- Locate the output speed sensor on the transmission housing (typically near the tail shaft or differential housing). Inspect the connector for corrosion, loose pins, or damage.
- Measure sensor resistance with a multimeter and compare to manufacturer specifications (typically 300-1200 ohms for a magnetic sensor). With the car safely raised and the gearbox in neutral, turn a drive wheel by hand and check that the sensor produces a signal.
- Compare input and output speed readings. Vehicle speed is standard OBD2 live data, but transmission input and output speeds usually need manufacturer-level software. The output speed should correlate with vehicle speed and the current gear ratio.
- If the sensor and wiring test normal, inspect the transmission fluid for metal contamination. Debris on the magnetic sensor tip can cause signal distortion.
How much does P0720 cost to fix?
Repair costs for P0720 vary depending on the root cause and your vehicle. Here are typical estimates:
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Output speed sensor replacement | €25–€120 | €60–€200 | €85–€320 | Moderate |
| Sensor wiring repair | €15–€60 | €80–€180 | €95–€240 | Moderate |
| Transmission fluid and filter change | €50–€150 | €80–€200 | €130–€350 | Moderate |
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0720 on specific vehicles
P0720 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:
P0720 on Mercedes-Benz
Mercedes C-Class (722.9)
Opel
Opel Astra
2004-2023
The Astra H and J with the Aisin AF17/AF22 automatic transmission trigger P0720 due to the output speed sensor failing from heat exposure. The sensor is located at the bottom of the transmission and is easy to access. A straightforward and inexpensive repair on these models.
Skoda
Skoda Octavia
2004-2024
Octavia models with the DQ200 and DQ250 DSG transmissions share the speed sensor design of the VW Golf. On DSG models, the sensor is part of the mechatronic unit, making individual replacement more complex.
P0720 on Ford
Ford Focus
Related diagnostic codes
These codes are often seen alongside P0720 or indicate related issues:
Common questions about P0720
- What does P0720 mean?
- P0720 means the output speed sensor on your transmission is not sending a valid signal. This sensor measures how fast the output shaft spins, which tells the car its road speed and helps the transmission decide when to shift.
- Can P0720 cause my speedometer to stop working?
- Yes. Many vehicles use the output speed sensor signal for the speedometer. If the sensor fails, your speedometer may read zero or fluctuate wildly, and cruise control will stop working.
- Is the output speed sensor easy to replace?
- On most vehicles, yes. The sensor is externally mounted on the transmission case and can be replaced with basic tools. The part costs 25-120 EUR and replacement takes 30-60 minutes for a competent DIYer.
- Can P0720 affect ABS and traction control?
- Yes. The ABS and stability control systems use vehicle speed data. A faulty output speed sensor can trigger ABS and ESP warning lights because the system detects conflicting speed signals.
- What is the difference between P0715 and P0720?
- P0715 relates to the input (turbine) speed sensor at the front of the transmission, while P0720 relates to the output speed sensor at the rear. The input sensor measures engine-side speed, the output sensor measures wheel-side speed.
Read our detailed guides
- Next stepHow to Find Out What Is Wrong With Your Car for 15 EurosA 15 euro Bluetooth adapter and a free phone app read the exact fault code a shop charges 30 to 100 euros to pull. Here is how to do it yourself in 5 minutes.
- Transmission Slipping: The $150 Check Before the $4,000 BillEngine revs rise but the car does not. Check the fluid first: a slipping automatic can be a $150 service or a $4,000 rebuild, and the tells differ.
- Transmission Repair Cost: Repair, Rebuild or Walk Away?Transmission repair costs $150 for a fluid service, $2,000 to $4,000 for a rebuild, or $3,000 to $5,500 for a reman unit. And when the car is not worth it.
- Check Engine Light Flashing? Stop Driving and Read This FirstA flashing check engine light means the engine is misfiring right now. Pull over and read the code: the fix is usually $80 to $400, the delay costs $1,500 up.
- Car Dashboard Symbols and Meanings: Warning Lights ExplainedAn unfamiliar symbol just lit up and you need to know whether to stop. Read the colour first, then find your symbol in the table: every one carries its verdict.
Scan your car with Skanyx to diagnose P0720
Your car logged P0720. Skanyx reads it on a standard OBD2 adapter (Bluetooth LE on iPhone), tells you whether it is safe to keep driving, and shows the €85-€350 repair range so you know the number before a shop quotes you. Free on iPhone and Android, and you do not need to be a mechanic to read it.
Get Skanyx freeGet the newsletter
New fault-code guides, real repair-cost data and seasonal car-care tips. No spam, unsubscribe anytime.
We only email about car diagnostics content. Privacy Policy