P0720 Code: Toyota Tacoma (2016-2023) - Causes, Symptoms & Fixes

Data note: Based on the provided NHTSA data for Toyota Tacoma (2016-2023), there are no recalls and no official complaints listed for P0720 in this model/year. No recalls found in NHTSA database.

CODE MEANING AND SEVERITY

• Code meaning: P0720 – Output Speed Sensor Malfunction. This pertains to the transmission’s output speed sensor (OSS) or its circuit. The OSS provides the transmission output shaft speed to the Powertrain Control Module (PCM/TCM) to help manage shifting and to supply vehicle speed data used by the speedometer and related systems.
• What it implies: The sensor signal or its wiring is not being read correctly by the PCM/TCM. Depending on the fault, the PCM may default to limp mode or risk incorrect shift points, speedometer mismatch, and impaired cruise control.
• Severity in a Tacoma context: Moderate to high. A faulty OSS/VSS signal can cause erratic or hard shifting, incorrect speed readings, cruise control issues, and potential driveability problems. In some cases, the vehicle may enter a fail-safe or limp mode to protect the transmission, limiting performance.
• Important note on data: No recalls found in NHTSA database for this issue on this model/year, per the provided data.

COMMON CAUSES ON TOYOTA TACOMA

• Faulty output speed sensor (OSS) or vehicle speed sensor (VSS) in the transmission.
• Damaged, frayed, or corroded wiring harness or connector at the OSS/VSS or where the harness runs near the transmission.
• Poor or intermittent electrical connection (loose connector, water ingress, dirt, corrosion).
• Grounding issues or voltage supply problems to the sensor (battery/alternator issues, blown fuse in the sensor circuit).
• PCM/TCM software corruption or a need for a software reflash/update (less common, but possible in some vehicles).
• Mechanical issues in the sensor mounting or movement (sensor alignment) or debris interfering with the sensor’s pickup.
• Intermittent faults that only appear when the transmission is under load or at certain temperatures.

SYMPTOMS

• Check Engine Light (MIL) may be on, sometimes with P0720 (and possibly related codes) stored.
• Transmission shifting anomalies: harsh shifts, delayed shifts, erratic upshifts or downshifts, or a shift into “limp”/fallback mode.
• Speedometer behavior: speed reading may be erratic, stuck at a value, or not read at all while driving; cruise control may disengage or become unreliable.
• Transmission may feel like it’s not accelerating normally or may operate in a reduced-range mode.
• In some cases, no obvious driveability issues other than a light or a pending code.

DIAGNOSTIC STEPS

Note: Use a professional-quality scan tool capable of reading transmission data and live sensor data. When needed, a mechanical/electrical test with a DVOM (multimeter) or an oscilloscope is helpful.

• Step 1: Confirm the DTC and capture freeze-frame data

  • Verify P0720 is current and note the recorded vehicle speed, engine speed, and any other related codes in the freeze-frame data. This helps determine whether the fault occurs while moving and at what speed.

• Step 2: Visual inspection and basic wiring check

  • Inspect the OSS/VSS sensor and its connector at the transmission for signs of damage, corrosion, dirt, or water intrusion.
  • Inspect the wiring harness near the transmission for fraying, kinks, pinching, or damaged insulation.
  • Disconnect and inspect the connector for bent pins or poor seating; reseat firmly if needed. Clean with electrical contact cleaner if corrosion is present.

• Step 3: Check sensor operation with a scan tool

  • With the vehicle moving (safely test in a controlled environment or a measured road test), observe the OSS/VSS signal in the scan tool.
  • Compare the vehicle speed readout on the scan tool to the actual road speed. A mismatch or zero speed when moving indicates an OSS/VSS issue.
  • If the tool shows no speed data or erratic values despite the vehicle moving, suspect the sensor or its circuit.

• Step 4: Circuit testing (sensor to PCM/TCM)

  • If you have wiring diagrams and the ability, backprobe the sensor connector to verify supply voltage (VCC or reference) and ground, and to check the signal line to the PCM/TCM.
  • Use a DVOM to check for:
    • Proper reference voltage at the sensor (as specified for Toyota transmissions; some sensors are 5 V references but verify against a factory manual).
    • A clean, duty-cycle or pulse-type signal on the signal line when spinning the sensor (requires spin the output shaft with the transmission in gear or a controlled test).
  • Look for voltage drops, short to ground, or open circuits in the sensor circuit.

• Step 5: Sensor testing (optional but informative)

  • If equipped with a testable OSS/VSS, verify its resistance or response per Toyota service specifications. Compare readings to the expected values in a service manual.
  • If an oscilloscope is available, view the sensor waveform while the transmission output shaft is rotated or during driving to confirm a clean, periodic signal.

• Step 6: Rule out related systems

  • Check battery health and charging system; weak voltage can cause sensor readings to appear faulty.
  • Check for other codes that suggest data bus or communication issues (e.g., miscommunication with the TCM/ECM), which can create or mask P0720.

• Step 7: Remedy decisions

  • If the OSS/VSS sensor or its connector is failed or shows poor signal, replace the sensor and repair/secure the harness as required.
  • If wiring is damaged beyond repair, replace the affected harness portion and reseal/coat connections to prevent moisture ingress.
  • If sensor and wiring test good but fault persists, consider PCM/TCM software update or replacement per dealer/service guidelines.
  • After any repair, clear codes and perform a road test to confirm the fault does not reappear and that Vehicle Speed matches actual road speed.

RELATED CODES

• P0720 family notes: P0720 (Output Speed Sensor Malfunction) often has related codes such as:
  • P0721, P0722, P0723 (Output Speed Sensor range/performance or circuit issues — subtypes depend on OEM interpretation)
• Other VSS-related codes to watch for:
  • P0500 (Vehicle Speed Sensor Malfunction) – not the same DTC family but related to speed signal problems.
• In Toyota TACOMA scenarios, these codes may appear in combination if multiple speed-sensor signals or circuits are affected.

REPAIR OPTIONS AND COSTS (2025 PRICE RANGES)

Prices vary by region, dealer vs independent shop, and whether additional related faults are found. The ranges below assume standard labor rates and typical parts costs.

• Vehicle Speed Sensor (VSS) / Output Speed Sensor (OSS) replacement

  • Parts: roughly $25–$120
  • Labor: roughly 0.5–1.5 hours
  • Typical total: roughly $100–$350
  • Notes: In many Tacomas, the OSS/VSS is mounted to the transmission and replacement is a straightforward bolt-in job; access and sensor type vary by transmission model.

• Wiring harness repair or connector replacement

  • Parts: $20–$200 (depends on extent and whether a new harness section is required)
  • Labor: 1–3 hours
  • Typical total: $200–$650
  • Notes: If wiring damage is localized and easily repaired, costs stay modest. More extensive harness repair can add hours.

• PCM/TCM software update or reflash

  • Parts: minimal (software)
  • Labor/Scan time: 0.5–2 hours
  • Typical total: $100–$450 (dealer or advanced independent shop)
  • Notes: A software update can fix calibration/interpretation of sensor data; some cases require a reprogram or a replacement unit if the PCM/TCM hardware is at fault.

• PCM/TCM replacement (less common for P0720 alone)

  • Parts: $350–$900 (PCM/TCM unit) plus
  • Labor: 2–6 hours (depending on access and immobilizer considerations)
  • Typical total: $900–$2,500
  • Notes: This is a last-resort scenario when fault cannot be resolved by sensor/wiring fixes and the PCM/TCM is confirmed defective by a technician.

• Transmission service (if additional mechanical issues are found)

  • Fluid, filter, seals, potential valve body work
  • Costs can vary widely; basic service around $100–$300; more extensive work can exceed $1,000 and approach several thousand for major transmission repairs.

Important: These are general cost ranges for 2025. Actual quotes will vary by location, shop, and any towing or diagnostic fees. If you’re working with a dealer or a shop, ask for a written estimate with labor hours and part costs before authorizing work.

DIY VS PROFESSIONAL

• DIY options (suitable for confident DIY enthusiasts):

  • Visual inspection of the OSS/VSS sensor and wiring.
  • Replacing a clearly faulty sensor if you can access it without removing the transmission. This is typically a straightforward bolt-in replacement.
  • Cleaning connectors and reseating; applying dielectric grease to protect connectors after cleaning.
  • Basic wiring checks with a multimeter (continuity, resistance) if you have the service manual or wiring diagrams.
  • Road testing after repair to verify that the speed signal and shifting behavior are back to normal.

• DIY caveats:

  • Electrical diagnosis can be tricky: you may misinterpret sensor signals without the proper equipment (e.g., oscilloscope or advanced scan tool).
  • Some Tacoma models place the OSS/VSS sensor in a location that requires substantial disassembly to access; if you’re not comfortable with transmission area work, consider a professional.
  • If the fault is PCM/TCM related or involves a voltage/ground issue beyond the sensor, professional diagnosis is recommended to avoid cascading electrical issues.

• When to go professional:

  • If sensor replacement does not resolve the issue.
  • If wiring harness damage is found or suspected but not easily repairable.
  • If PCM/TCM software updates or replacements are required, or if there are multiple fault codes indicating data communication problems.
  • If you lack proper tools (oscilloscope, professional-grade scan tool) or confidence with automotive electrical diagnostics.

PREVENTION

• Regular inspection of the transmission wiring and OSS/VSS sensor connections, especially after exposure to water, mud, or off-road driving.
• Keep electrical connectors clean and dry; use dielectric grease on connector seals to help resist moisture ingress.
• Ensure the battery and alternator are healthy; voltage dips can create sensor signal anomalies.
• If you do a lot of off-roading or severe driving, inspect the sensor area periodically for debris or damage and address promptly.
• If you notice erratic speed readings or shifting issues, address them early rather than driving long distances with a lingering P0720.
• Stay current with any Toyota service advisories or recalls (even if none exist for your specific VIN) and perform periodic software updates as recommended by Toyota.

Final notes

• The guide above focuses on P0720 as it relates to a 2016–2023 Toyota Tacoma, using general automotive diagnostic practices. The provided data indicates no NHTSA recalls or reported complaints specifically for this issue in this model/year. If you experience P0720, start with the sensor and wiring inspection and proceed through the diagnostic steps outlined. If in doubt, consult a qualified technician to avoid misdiagnosis and potential transmission damage.