P0720 Code: Dodge Ram 1500 (2019-2024) - Causes, Symptoms & Fixes

2019-2024 Dodge Ram 1500 P0720 Diagnostic Guide

Important data note:

• No recalls found in NHTSA database
• No owner complaints recorded for this make/model/year/issue combination
• No recalls or TSBs cited in the data you supplied
• Data limitations: absence of complaints/recalls does not guarantee the issue isn’t common; it just means the official dataset here shows none. Use this guide as a diagnostic framework informed by general automotive transmission knowledge and common P0720 behavior on modern Rams.

CODE MEANING AND SEVERITY

• P0720 = Output Speed Sensor Circuit Malfunction
• What it means: The transmission control system detects an abnormal condition with the output speed sensor (OSS) circuit. The OSS provides a speed signal from the transmission’s output shaft to the Transmission Control Module (TCM). If the signal is erratic, out of range, or absent, the TCM may set P0720.
• Severity and impact:
  • Drivability: Can range from mild to serious. Some drivers notice hard shifts, delayed or harsh/rough shifting, or a vehicle that won’t shift properly. In some cases the transmission may go into a fail-safe/limp mode to prevent damage.
  • Dash indicators: Check Engine light likely illuminated; transmission/dashboard lights may also come on. Speedometer behavior can be affected (erratic or incorrect speed readings).
  • Long-term risk: Prolonged symptoms can contribute to accelerated wear of internal transmission components if the TCM relies on a faulty speed signal for shift timing.

COMMON CAUSES ON DODGE RAM 1500

• Faulty OSS sensor itself (sensor failure or internal wiring fault)
• Damaged or corroded OSS wiring or connectors (pin damage, broken insulation, short to ground or supply, water ingress)
• Poor or loose electrical connections at the OSS connector or ECU/TCM side
• Wiring harness chafing or rubbing near the transmission or crossmember
• Transmission Control Module (TCM) or PCM software issues (calibration or fault in signal processing)
• Intermittent fault or internal transmission mechanical issue that affects the OSS signal (e.g., output shaft misalignment or gear wear creating an irregular signal)
• Less common: sensor supply/ground issues, or a fault that’s masking another speed-sensing problem (e.g., ISS or another related sensor code coexisting)

SYMPTOMS TO EXPECT

• Shifts: delayed shifts, harsh or clunky/jerky upshifts or downshifts, slipping at certain speeds
• Transmission behavior: may go into limp mode or default to a particular gear; erratic or no response to throttle input
• Speedometer/cruise control: speedometer reading may be erratic or incorrect; cruise control may behave unpredictably
• Dashboard lights: Check Engine Light on; TCM/transmission warning lights may illuminate
• Possible ancillary codes: other P07xx codes (related to transmission speed sensors or gear ratios) may appear or the vehicle may display a generic transmission fault

DIAGNOSTIC STEPS

Note: Always start with secure, safe operation. If you suspect a transmission issue, diagnose with the engine off and battery disconnected before disconnecting any connectors. Then reconnect and test in a controlled environment.

A. Verify and gather data

• Use an OBD-II scanner to confirm P0720 and note any freeze-frame data (vehicle speed at the time, engine RPM, transmission gear position, etc.).
• Check for any related codes (P0710 – Input Speed Sensor Malfunction, P0725 – gear ratio/sensor issues, P0700 – transmission control fault, etc.). Document all codes and freezing frames.

B. Visual inspection

• Inspect OSS wiring harness and connector at the transmission for visible damage, corrosion, oil/water intrusion, or loose pins.
• Inspect for damaged or pinched wires along the harness path (especially around the sensor, harness near the bell housing, and where it runs along the transmission tunnel).
• Check for leaks or contamination around the OSS sensor area (transmission fluid leaks can degrade electrical connections).

C. Electrical checks

• Disconnect the OSS connector and inspect pins for bent or damaged terminals; reseat firmly.
• With the ignition off, perform a visual resistance check of the OSS circuit if you have factory service information (compare readings to the manufacturer spec in the service manual). If you don’t have exact spec, note whether the circuit shows open, short to ground, or short to power.
• Check continuity from OSS connector to the TCM/ECU pin in the harness in the engine bay or inside the driver's side kick panel area (follow service manual wiring diagrams). Look for abnormal resistance or opens.
• Look for shorts to power or ground in the OSS circuit when wiggling the wiring gently to identify intermittent faults.
• If possible, monitor the OSS signal live with a scope or advanced scan tool while slowly driving and changing gears. An OSS signal that is noisy, erratic, or flatlines as vehicle speed changes is a strong indicator of OSS or wiring fault.

D. Sensor testing and replacement

• If OSS shows signs of failure or erratic electrical behavior, replace OSS with an OEM or high-quality equivalent. After replacement, clear codes and test drive to confirm P0720 does not reappear.
• Re-test after reseating or replacing connectors; apply dielectric grease to ensure moisture protection.

E. Check transmission software and re-learn procedures

• Some cases are resolved or mitigated by a TCM/ECU software update or reflash. Check for available software updates via official Mopar/Chrysler service channels or the dealership.
• Some transmissions require adaptive learning resets after component replacement; perform the appropriate TCM adaptation or reset as per service manual.

F. If no fault found in OSS/wiring

• Consider deeper transmission diagnosis. Internal transmission issues (valve body wear, gear train issues) can sometimes present as OSS-related symptoms if they alter timing signals or speed readings or cause TCM to misinterpret signals. A professional may need to perform more in-depth tests (valve body check, pump pressure tests, or gear ratio monitoring) if P0720 persists after OSS/wiring replacement.

G. Test drive and verification

• After any repair, perform a timed drive covering highway and city speeds to ensure that shifts are smooth, the speedometer reads correctly, and no new codes appear.

RELATED CODES

• P0710 – Input Speed Sensor Malfunction (ISS signal issues can sometimes accompany OSS problems)
• P0725 – Output Speed Sensor Range/Performance (alternative OSS-related code in some applications)
• P0700 – Transmission Fault (generic catch-all; may accompany P0720 if the TCM detects multiple issues)
• P0730 – Wrong Gear Ratio (may occur if OSS signal is inconsistent and the TCM selects incorrect gears)
  Note: The presence of related codes can help pinpoint whether the problem is sensor-related, wiring-related, or more deeply mechanical/TCM-related.

REPAIR OPTIONS AND COSTS (2025 PRICES)

Prices vary by region, shop, and whether the work is done at a dealer vs independent shop. The figures below are ballpark ranges to help with budgeting.

• OSS sensor replacement
  • Parts: roughly $20–$120 (OEM vs aftermarket)
  • Labor: about 1–2 hours
  • Typical total: $150–$420
• Wiring harness or connector repair
  • Parts: $20–$100 (connector/repair kit as needed)
  • Labor: 0.5–2 hours depending on access
  • Typical total: $100–$350
• TCM/ECU software update or reflash
  • Parts: usually included in service or software cost
  • Labor: $60–$180
  • Typical total: $60–$200 (or more if dealer-based diagnostic time is charged)
• Internal transmission issues (less common for P0720)
  • If the OSS/wiring is ruled out and the TCM is up-to-date, persistent symptoms may require transmission service, valve body work, or in rare cases a rebuild/replacement.
  • Diagnostic fees and initial inspection typically $100–$150 at shops; transmission work can quickly rise to $1,000–$3,000+ depending on scope.
• Diagnostic fee (if applicable)
  • Many shops charge a diagnostic fee if you don’t have a current diagnosis; typical range: $90–$150.

Important note: Because the provided data shows no recalls and no complaints in the dataset, the cost ranges above are based on typical repair scenarios for OSS-related failures and common transmission service in modern Rams. If a dealer or shop identifies a different root cause (e.g., internal transmission failure or TCM fault beyond software), costs will be higher.

DIY vs PROFESSIONAL

• DIY-friendly opportunities
  • Visual inspection of OSS wiring and connectors; reseating or replacing a corroded/loose connector.
  • Checking for obvious wiring damage (chafed insulation, oil contamination, moisture) and addressing it.
  • Replacing the OSS sensor if you’re comfortable with basic electrical work and can access the sensor location.
  • Basic software updates or re-flashes are typically done via dealer or professional diagnostic tools; attempting a software update without proper tooling is not recommended.
• When to go professional
  • If you cannot confidently diagnose OSS vs wiring vs TCM, or if the transmission requires removal to access the sensor or wiring.
  • If the vehicle shows intermittent symptoms or the OSS test results are inconclusive.
  • If you suspect internal transmission faults (valve body, gear train) or if software updates do not resolve P0720.
  • Transmission work requires specialized tools, torque specs, and procedures; a trained technician is recommended.
• Safety and warranty considerations
  • Disconnecting the battery and working around the transmission can be hazardous; follow proper safety procedures.
  • If the vehicle is under warranty, dealer service may be required for certain OSS or TCM-related repairs.

PREVENTION

• Regular transmission maintenance
  • Use the manufacturer-recommended transmission fluid specification and level checks. For Ram 1500, this commonly involves Dexron-spec or Mopar transmission fluid as per the owner's manual. Follow service intervals for fluid changes and MB (maintenance) checks.
  • Inspect for leaks around the transmission and OSS area; fix leaks promptly to protect electrical connections.
• Electrical system care
  • Inspect the OSS wiring harness route for wear or damage during routine maintenance; protect harnesses with loom if needed.
  • Keep connectors clean and dry; use dielectric grease on connectors during reassembly to resist moisture ingress.
• Avoid harsh conditions that strain the transmission electrical system
  • Avoid aggressive towing or heavy towing loads that exceed the vehicle’s design limit without proper cooling and maintenance.
  • When operating in water-crossing situations or heavy rain, ensure electrical connectors stay dry and sealed.
• Use quality replacement parts
  • When replacing the OSS sensor, use OEM or high-quality equivalents designed for the Ram 1500 transmission.
  • Ensure software/TCM updates are performed by qualified technicians to prevent reoccurrence or compatibility issues.

Summary

• P0720 on a 2019–2024 Ram 1500 indicates an OSS circuit malfunction. The most common culprits are the OSS sensor itself or its wiring/connectors, but don’t rule out TCM/software issues or less common internal transmission concerns.
• Diagnosis should prioritize: confirm code, inspect and test OSS wiring and connector, test/replace OSS if needed, and check for software updates.
• No recalls or official complaints were listed for this exact scenario in the provided data; use the guide as a structured diagnostic path rather than evidence of widespread prevalence.
• Costs vary; expect OSS replacement and basic wiring repair to be in the low hundreds, with higher costs if TCM software, more extensive transmission work, or dealer-level service is required.
• DIY steps can handle wiring and sensor replacement if you have electrical/test tool access; for complex faults or transmission internal work, a professional technician is recommended.