P0720 Code: Honda Accord (2018-2023) - Causes, Symptoms & Fixes

No recalls found in NHTSA database.

No NHTSA complaints found for this make/model/year/issue combination.

Code: P0720 on a 2018-2023 Honda Accord should be interpreted with the same fundamentals as in other vehicles: it points to an Output Shaft Speed Sensor (OSS) circuit malfunction. In practice, P0720 means the transmission control module (TCM/ECU) is not seeing a valid OSS signal, or the signal is out of expected range. That can affect shifting, speed sensing, and transmission behavior. However, note that the data you provided shows no NHTSA complaints or recalls for this specific combo, so real-world incidence in this dataset is not established.

CODE MEANING AND SEVERITY

• What it means: P0720 = Output Shaft Speed Sensor Malfunction. The OSS tells the TCM how fast the transmission output shaft is rotating. The TCM uses this information to time gear changes and synchronize shift points.
• Why it matters: If the OSS signal is missing or erratic, the vehicle may not shift properly, can go into limp mode, or the speedometer may read inaccurately. In some cases the engine/transmission computer may limit performance to protect the drivetrain.
• How severe on a 2018-2023 Accord: Moderate to potentially high. If left unresolved, shifting irregularities or drivability issues can worsen and the transmission could be driven in a degraded state.

COMMON CAUSES ON HONDA ACCORD

• Faulty OSS sensor itself.
• Damaged, corroded, or loose wiring harness between the OSS and the TCM/ECU.
• Faulty or corroded sensor connectors (pin corrosion, moisture ingress, improper mating).
• Ground or power supply issues affecting the OSS circuit.
• Water intrusion or high-vibration exposure near the sensor area.
• Transmission control module software/calibration fault or the need for an update.
• Less commonly: internal transmission issues that upset the sensor readings or misbehavior that triggers a fault code.

SYMPTOMS

• Check Engine Light (CEL) with P0720 stored.
• Transmission shifting oddly: harsh or delayed shifts, hunting between gears, slipping, or erratic upshifts/downshifts.
• Possible speedometer irregularities: phantom speeds, intermittently dropping to zero, or not matching road speed.
• In some cases, the car may enter a “limp mode” or reduced-power condition to protect the drivetrain.
• Cruise control may be affected if vehicle speed data is suspect.

DIAGNOSTIC STEPS

Note: Start with the simplest, least invasive checks and progress to sensor/harness replacement if needed.

• Step 0 — Confirm and document

  • Read DTCs with a reputable scan tool; write down freeze-frame data (speed, RPM, transmission gear, etc.).
  • Confirm P0720 is present and note any related transmission codes that may accompany it (P0700 family/other speed sensor codes).

• Step 1 — Visual inspection

  • Inspect the OSS sensor and its wiring harness for obvious damage, rubbing, or heat exposure.
  • Check for chipped insulation, exposed conductors, or corrosion on connectors.
  • Look for signs of moisture or water intrusion in the connector or harness near the transmission.

• Step 2 — Check harness continuity and resistance

  • With the battery disconnected, carefully unplug the OSS connector and test the wiring from the connector to the PCM/TCU harness side for continuity.
  • Look for shorts to power or ground and open circuits. Inconsistent or high-resistance readings can indicate a damaged wire or bad connector.
  • Check for proper pin seating and ensure the grounds/power feeds to the OSS circuit are solid.

• Step 3 — Inspect the OSS sensor itself

  • If accessible, measure the sensor resistance (per Honda’s service manual values). Compare to spec; a filter or reluctor issue may show abnormal resistance or nonfunctional output.
  • If the sensor is a Hall-effect type, you may observe no output or a flat signal if the element is failed.

• Step 4 — Live data testing with a scan tool

  • With the car running, monitor OSS output while slowly increasing and decreasing vehicle speed (either by road test or controlled environment).
  • Compare OSS speed signal to actual vehicle speed/VSS data (if your tool provides VSS). The OSS should output a stable signal that correlates with speed; a missing signal or large discrepancy indicates sensor or wiring fault.
  • Check for noise, jitter, or dropouts in the OSS data stream.

• Step 5 — Grounding and power integrity

  • Confirm battery voltage is stable (12.6+ volts engine off, >13V with engine running).
  • Inspect and test relevant ground points for corrosion, looseness, or poor attachment.
  • Check for voltage drop in the OSS power/ground circuit under load.

• Step 6 — Scan for software/TCU issues

  • Check for available ECU/TCU software updates or recalls (per your data, none are listed in the provided dataset). If updates exist from Honda, consider applying them after diagnosing hardware.
  • Some cases require TCU re-learn or calibration after sensor replacement.

• Step 7 — Decide on replacement or repair

  • If wiring is damaged beyond simple repair, or the sensor itself shows failure after testing, replacement is indicated.
  • If wiring/connector repairs restore proper signal and no other codes appear, you may avoid more extensive transmission work.

• Step 8 — Post-repair verification

  • Clear codes and perform a road test to ensure P0720 does not return.
  • Confirm normal transmission operation and that the speedometer is reading correctly.
  • Re-check for any new codes after a test drive.

RELATED CODES

• Transmission speed sensor family / related circuit codes may appear alongside P0720 if there are sensor or harness issues. Examples (general categories, not guaranteed precise numbers for every model/year):
  • P0715 / P0716 (Input/Turbine Speed Sensor circuit-related codes)
  • P0721 (Output Shaft Speed Sensor Range/Performance) — often appears in the same family of OSS-related diagnostics
  • P0700 (Transmission Control Module Malfunction Detected) — a generic umbrella code that can accompany sensor fault conditions
• Data limitations: The above codes are representative of common transmission-speed-sensor groupings; exact Honda Accord 2018-2023 code set can vary by software/TCU version and market.

REPAIR OPTIONS AND COSTS (2025 PRICES)

Prices vary by region, shop, and whether OEM parts are used. The following ranges assume typical labor rates and parts pricing in the U.S. for 2025.

• DIY OSS sensor replacement (most straightforward option)

  • Parts: OSS sensor (aftermarket: $20–$90; OEM: $60–$140)
  • Labor/tools: Performed by a capable DIYer; 1–2 hours
  • Estimated total: $20–$140 (plus tax) depending on sensor choice and any minor incidental costs (gaskets, connectors)

• Professional replacement with sensor + harness check

  • Parts: OSS sensor $60–$140; connectors/boots if needed $5–$30
  • Labor: 1–2 hours (shop rate roughly $90–$150/hr)
  • Estimated total: $170–$450
  • Notes: Often includes a transmission data check and a test drive after replacement

• Transmission wiring/connector repair or harness replacement

  • Parts: minimal if simply repairing a connector; wiring harness sections may require more
  • Labor: 1–3 hours
  • Estimated total: $120–$900 depending on extent

• Transmission service or potential internal issues

  • If the OSS fault is a symptom of broader transmission problems, costs can escalate
  • Transmission service/rebuild or replacement can range from approximately $2,000 to $6,000+ depending on condition, parts, and whether a used or rebuilt unit is installed
  • OEM vs aftermarket: OEM parts and dealer service typically cost more; reputable independent shops may offer lower prices

DIY vs PROFESSIONAL

• DIY feasibility: If you have basic electrical diagnostic skills, can access the OSS connector, and have a multimeter or scan tool, you can perform a careful inspection of wiring, connectors, and perform live-data checks. Replacing the OSS sensor yourself is feasible on many Accord transmissions, but access varies by model year and trim.
• Professional advantages: A trained technician can quickly:
  • Confirm sensor vs wiring faults with proper diagnostic procedures
  • Perform controlled measurements (oscilloscope tests, precise resistance checks)
  • Rule out PCM/TCU software issues and re-learn procedures
  • Ensure correct torque and alignment during sensor replacement
• When to bring it in: If you observe a consistent P0720 signal after a basic visual check, or if you lack the tools to perform live-data testing, a professional diagnosis is advised to avoid unnecessary part replacements.

PREVENTION

• Follow Honda’s transmission maintenance recommendations (use the correct ATF: DW-1 for many Honda automatics; verify your specific vehicle manual).
• Regularly inspect the transmission area for leaks, heat damage, and wiring harness integrity.
• Keep electrical connections clean and dry; replace degraded connectors or gaskets promptly to prevent moisture intrusion.
• Avoid prolonged exposure to high under-hood temperatures and road debris near the transmission area.
• If you replace the OSS sensor, consider inspecting nearby wiring for abrasion or pinching and re-torque or reseal connectors as recommended.
• Software updates: Ensure the TCM/ECU software is up to date if Honda has released relevant updates; some updates address sensor signal handling or fault thresholds.
• Use OEM or high-quality aftermarket sensors and connectors to minimize compatibility and corrosion issues over time.

Important data caveat

• The data you provided shows no NHTSA owner complaints and no recalls for this specific make/model/year/issue combination. That means there is no official complaint or recall history to cite for this scenario in the dataset. The diagnostic guide above uses general automotive principles and Honda-Accord-specific tendencies where known, but it is not based on reported incidents in the provided dataset. If you want the most current, model-year-specific information, checking the latest NHTSA data and Honda service bulletins or TSBs would be prudent.

If you’d like, I can tailor this guide further to your exact Accord trim, year, and whether you have a 1.5T or 2.0T engine with the 10-speed automatic, since sensor access and test steps can differ slightly between transmissions.