No recalls found in NHTSA database.
No NHTSA complaints were found for 2017-2023 BMW 5-Series related to P0720 (Output Shaft Speed Sensor Circuit) in the data provided.
CODE MEANING AND SEVERITY
- What P0720 means: P0720 is a transmission-related diagnostic code indicating a fault in the Output Shaft Speed Sensor (OSS) circuit. The OSS provides the transmission’s final-drive speed signal to the transmission control module (TCM). When the signal is out of range, erratic, or absent, the TCM may mismanage gear selection.
- How severe it is: Moderate to high. If the OSS signal is unreliable, the TCM may shift harshly, delay or fail to upshift/downshift, or place the powertrain in a safe/limp mode. In some cases the car may still drive but with compromised performance and fuel economy, and potentially risk of drivability issues if ignored.
COMMON CAUSES ON BMW 5-SERIES
- Faulty OSS sensor on the transmission (the sensor itself may be worn or damaged).
- Damaged, corroded, or loose OSS wiring harness or electrical connector to the sensor or to the TCM (including bent/poorly seated pins, exposed conductors, or pin corrosion).
- Intermittent or persistent short to power, short to ground, or open circuit in the OSS circuit.
- Transmission control module (TCM) issue or software calibration/update needed.
- Transmission fluid problems (contamination or degraded fluid) can contribute to sensor readings via affected electronics or seals, though the OSS fault is the electrical signal issue itself.
- Related sensors and circuit interactions (e.g., speed signal interactions with vehicle speed signal paths) could surface related DTCs that mimic or accompany P0720.
SYMPTOMS
- Harsh, erratic, or delayed shifting; occasional failure to upshift or downshift properly.
- Gear indicator may briefly show the wrong gear or the transmission enters a degraded mode (limp mode) to protect itself.
- Check Engine/Transmission fault lights illuminate; other transmission-related codes may appear.
- Possible abnormal speed readings or discrepancies between vehicle speed and engine/timing behavior.
- In some cases, you may notice poor acceleration or a feeling of “drag” as the TCM tries to compensate for faulty signal.
DIAGNOSTIC STEPS
Note: Use a BMW-specific diagnostic tool (ISTA, any compatible OBD-II scanner with live data and the ability to read BMW TCM data) to view real-time OSS data and freeze-frame info. Also verify there are no conflicting codes from ABS/DSC modules or other control units.
Step 0: Prepare
- Confirm the code P0720 is current and note any related codes (P071X, P073X, etc.). Check freeze-frame data for engine rpm, vehicle speed, transmission temperature, and current gear at the time of the fault.
- Ensure the vehicle has fresh battery voltage and no obvious hydraulic leaks; document any recent work on the transmission.
Step 1: Visual inspection
- Inspect the OSS sensor and its connector at the transmission for signs of damage, corrosion, oil or coolant contamination, loose or bent pins, and damaged wiring insulation.
- Inspect the wiring harness along its entire route for chafing, abrasion, or damage from movement, heat, or road debris.
- Check grounds and sensor mounting for proper torque and sealing.
Step 2: Electrical checks (circuit-level)
- With ignition off, inspect the OSS connector for proper seating; reseat if needed.
- Perform continuity and resistance checks on the OSS circuit between the sensor and the TCM/connector pin, looking for opens, shorts to ground, or shorts to power. Compare readings to OEM spec if available.
- Check for voltage supply at the OSS sensor when the ignition is on (the sensor typically runs on the vehicle’s 12V/relay circuit through the wiring harness). Look for a stable supply and no abnormal voltage drop under load.
- Check for a clean ground reference at the sensor and at the TCM/ECU. A bad ground can cause erroneous readings.
Step 3: Sensor condition test
- If possible, test the OSS sensor signal with a scope or a diagnostic tool that can display the output vs RPM. A healthy OSS should show a clean, proportional signal that changes smoothly with engine/transmission speed. A flat, noisy, or irregular signal indicates a faulty sensor or wiring issue.
- If the OSS signal looks normal but the code persists, suspect a poor connection or a TCM fault.
Step 4: Vehicle dynamics tests
- Clear the codes, drive in a controlled manner, and monitor real-time OSS data and gear status. If P0720 returns and the OSS data remains inconsistent or out of range, replace the OSS sensor or repair the harness as indicated by the findings.
- If the OSS wiring and sensor tests pass but P0720 recurs, consider a TCM software update or reprogramming per BMW procedures.
Step 5: Related diagnostic consideration
- Verify there are no related codes indicating a broader transmission fault (e.g., misbehavior in speed signals, other sensor circuits, or communication networks). Treat P0720 as potentially cascading from another fault if multiple codes are present.
RELATED CODES
- P0710 or P0711 (Input Shaft Speed Sensor circuit faults) - sometimes seen in systems that monitor multiple speed sensors.
- P0721 / P0722 / P0723 (Output Shaft Speed Sensor circuit performance or no signal; values vary by OEM) - may accompany P0720 or appear as alternate subcodes.
- P0700 (Transmission Control System Mal malfunction) or P0701 (Transmission Control System Range/Performance) - generic transmission fault codes that can appear in combination with P0720.
- P077X or P086X family (deeper hydraulic or control path issues) could be contextually related if the fault escalates.
Note: BMW and manufacturers may use different subcodes for OSS-related faults; always review the exact DTC wording and subcodes your scan tool provides.
REPAIR OPTIONS AND COSTS (2025 PRICES)
Prices are estimates for typical North America repair shops and may vary by region, labor rate, and whether parts are OEM or aftermarket.
OSS (Output Shaft Speed) sensor replacement
- Parts: $25–$120
- Labor: 1–2 hours
- Estimated total: $150–$400
- Notes: Sensor replacement is often straightforward but may require transmission access. Ensure proper torque and seal replacement if sensor uses an O-ring or gasket.
Wiring harness/connectors repair or replacement
- Parts: $10–$150 (harness segments or connector kits)
- Labor: 1–3 hours
- Estimated total: $150–$600
- Notes: Include weatherproof sealant or dielectric grease for connectors; may involve replacing sections of harness or re-terminating pins.
Transmission control module (TCM) software update or reflash
- Parts: minimal (software)
- Labor: 0.5–2 hours
- Estimated total: $100–$300
- Notes: Software updates can address calibration issues that trigger false OSS faults.
Transmission oil/fluid service (ATF) and filter change
- Parts: $20–$60 (ATF and filter)
- Labor: 1–2 hours
- Estimated total: $150–$350
- Notes: Use BMW-approved ATF; contaminated fluid can contribute to transmission sensor issues or overall performance.
TCM replacement (rare, if faulty)
- Parts: $600–$1,200
- Labor: 2–4 hours
- Estimated total: $1,000–$2,500
- Notes: Replacement is less common; ensure proper reprogramming and compatibility with the vehicle’s VIN and options.
Full transmission service or rebuild (extreme cases)
- Parts/Labor: $1,500–$4,000+ depending on extent
- Notes: Only in cases of widespread transmission failure or multiple related codes.
DIY VS PROFESSIONAL
DIY potential
- OSS sensor replacement is accessible to a capable DIYer with a basic shop setup (vehicle raised, proper tools, and attention to electrical harnesses). You should be comfortable disconnecting the battery, handling electrical connectors, and performing a sensor replacement with attention to torque and sealing surfaces.
- Pros: Lower cost, quick turnaround, educational experience.
- Cons: Risk of incorrect diagnostics, damaged wiring, or improper reassembly leading to further issues; you may miss related faults that a professional scanner would identify.
Professional route
- Pros: Comprehensive diagnostic with BMW-specific tools (ISTA), accurate interpretation of DTCs, correct sensor/Harness replacement, and proper reprogramming if needed. Guarantees the repair with typical warranty coverage on parts/labor.
- Cons: Higher upfront cost.
When to choose professional
- If you don’t have reliable access to BMW-specific diagnostic tools, or if the OSS wiring is damaged, or if the vehicle is in limp mode and you need a definitive repair quickly.
- If multiple related codes are present, or if the problem persists after a sensor replacement.
PREVENTION
Regular transmission maintenance
- Use the correct BMW-approved ATF specification for your model and ensure proper fill level. Incorrect fluid type or overfill/underfill can cause sensor readings to behave unpredictably.
- Keep the cooling system for the transmission and engine in good shape; excessive heat can degrade electrical components and reduce sensor life.
Monitor and address leaks promptly
- Oil, coolant, or ATF leaks around the transmission/OSS area can contaminate connectors or sensors; fix leaks promptly to protect sensors and wiring.
Protect wiring and connectors
- Inspect the OSS harness routing during routine services; ensure there is no chafing or pin damage from road debris or heat sources. Use loom or protection where needed.
Software updates
- Ensure software for the TCM/TCM-calibrated modules is up to date as BMW software updates can address sensor signal reliability.
Drive behavior
- Avoid aggressive shifts or repeated deep launches that can stress the transmission and its sensors. Allow the transmission to warm up in cold weather when required.
Early diagnostics
- If a P0720 code appears, address it promptly rather than driving long distances with a suspect OSS circuit. Early repair reduces the risk of collateral transmission damage.
Summary
- P0720 on a 2017–2023 BMW 5-Series generally points to an OSS circuit fault—sensor, wiring, or TCM calibration. Diagnostic steps prioritize a thorough electrical check of the sensor and harness, real-time OSS data, and confirmation with BMW-specific scan tools. Repair options range from sensor or wiring repair to software updates or, in rare cases, TCM replacement. Based on 2017–2023 data, there are no listed NHTSA recalls or complaints in the provided dataset for this issue, so no recalls are currently documented here. If you see P0720, address promptly to avoid transmission performance issues or limp-mode scenarios.