Comprehensive diagnostic guide for P0720 on 2021-2024 Dodge Durango
Data note and limitations
- NHTSA data shown: No owner complaints found for this exact make/model/year/issue combination.
- NHTSA recalls: No recalls found in the database for this combination.
- Because there are no listed complaints/recalls in the provided data, this guide relies on general automotive knowledge for the P0720 diagnosis and Durango-specific transmission layout, not on a large set of official complaint statistics. Treat this as a practical guide that may need to be adapted to your vehicle’s behavior and any updated service information from Dodge/Chrysler.
CODE MEANING AND SEVERITY
- Code: P0720 — Output Shaft Speed Sensor Circuit Malfunction (often called OSS sensor or Output Speed Sensor circuit fault).
- What it means: The transmission’s output speed sensor (OSS) is not producing a valid signal or the PCM/TCM isn’t correctly reading the signal. The OSS provides crucial data about the transmission’s output shaft speed, which the transmission control module uses to determine gear selection and shift timing.
- Severity on a Dodge Durango (2021–2024): High. In many cases, this can lead to improper or failed shifting, shifting delays or harsh shifts, incorrect gear selection, speedometer errors, and even limp/fail-safe mode to protect the transmission. If the signal is out of range or intermittent, the vehicle may still drive but with noticeable transmission behavior problems and warning light(s).
COMMON CAUSES ON DODGE DURANGO
- Faulty OSS sensor itself: worn, damaged, or failed sensor.
- Damaged or corroded wiring harness or connector: open/shorts, damaged insulation, moisture intrusion, or loose connections at the OSS harness or the PCM/TCM connector.
- Damaged or misaligned tone wheel on the transmission output shaft: missing teeth, bent/loose tone wheel, or misalignment leading to improper signal pickup.
- PCM/TCM software or calibration issue: outdated or corrupt software can misinterpret legitimate OSS data.
- Sensor ground or power issues: poor grounding or supply voltage faults affecting sensor operation.
- Transmission fluid concerns: very degraded or incorrect ATF can indirectly affect sensor readings or cause electrical noise; contamination can affect sensor signals or timing.
- Mechanical or driveline disruption near the sensor: metal debris, bearing wear, or other mechanical issues causing irregular OSS signal generation.
- Connector/contamination at the sensor area: oil leaks or dirt/oil buildup around the sensor or harness connectors can cause poor signal transmission.
SYMPTOMS YOU MIGHT SEE
- Check Engine or Transmission warning light(s) on or flashing.
- Transmission may not shift correctly, shift points feel late or abrupt, or it may go into fail-safe/limp mode.
- Speedometer may be incorrect or stop reading correctly; cruise control may behave erratically or disengage.
- Harsh or delayed upshifts and/or downshifts.
- Vehicle may appear to “slip” or fail to engage the desired gear.
- Inconsistent trans temp or odd data in the TCM/PCM live data stream when scanned.
- Depending on the vehicle and scanner, you may see P0720 stored or current, possibly with related codes (e.g., P0715, P0721, P0716) appearing as the system tries to interpret the fault.
DIAGNOSTIC STEPS
Note: Start with a correct, current scan tool that can read live transmission data (including OSS pulse data) and freeze-frame data. Document all codes and live data before disassembly.
A. Confirm the fault
- Use a capable scanner to confirm P0720 is current (not only stored) and note any related codes.
- Check freeze-frame data for vehicle speed, RPM, transmission gear, and OSS-related readings at the time of the fault.
B. Visual and mechanical inspection
- Inspect OSS sensor and its wiring harness for obvious damage, corrosion, oil leaks, or abrasion at the connector, near the transmission housing, and along the harness.
- Disconnect and inspect the OSS connector for corrosion, bent pins, or foreign material. Reconnect firmly.
- Inspect the transmission output shaft area for damage to the tone wheel and for any debris or misalignment.
- Check for any recent transmission work that could have disturbed wiring or sensor alignment.
C. Electrical tests on the OSS circuit
- With ignition on (engine off) and key in run, perform a resistance/continuity check of the OSS wiring from the sensor to the TCM/PCM connector (or to the body harness splice, depending on routing). Look for opens, shorts to power, or shorts to ground.
- Check sensor power and ground at the sensor connector. Ensure the supply voltage is within spec and the ground is solid.
- If possible, view the OSS signal with the scan tool or an oscilloscope. The OSS typically generates a pulse or frequency signal proportional to output shaft speed. Look for a clean, periodic waveform without dropouts or erratic spikes. Intermittent signals can indicate a failing sensor or a damaged tone wheel/wiring.
D. Sensor and tone wheel verification
- If the tone wheel and sensor alignment can be visually inspected, verify the sensor mounting position and teeth/varnish on the tone wheel. A damaged or dirty tone wheel can produce irregular signals.
- If the sensor is removable and you have the skill/tools, consider replacing the OSS sensor as a test (see Repair Options). If you replace the sensor and the fault clears, the OSS was the cause.
E. Transmission fluid and cooling considerations
- Check ATF level and condition (color, smell, contamination). Low or degraded ATF can complicate transmission electronics behavior. If the fluid is old or contaminated, perform a proper ATF service if indicated by service guidelines.
- Inspect for leaks that could contaminate the sensor area and onboard electronics.
F. Software and updates
- Check for any available TCM/PCM software updates or recalls/TSBs from Dodge that address transmission control sensing. If an update exists and is applicable, perform it according to manufacturer guidelines.
G. If OSS test/visual checks are inconclusive
- Consider additional testing with live data: monitor OSS signal versus actual vehicle speed and RPM. Look for mismatch, dropouts, or signal intermittency that correlates with fault symptoms.
- If the OSS signal looks good but P0720 persists, broaden the diagnosis to related circuits (P0715/P0716; P0721/P0722) and possible PCM/TCM faults or an internal transmission issue.
H. Final decision path
- If a faulty OSS sensor or wiring is confirmed or strongly suspected: replacement or repair is warranted.
- If signals are intermittent but sensor and wiring tests pass, consider software updates, TCM reprogramming, or more in-depth transmission inspection.
- If a mechanical failure in the transmission’s internal components is suspected (tone wheel, carrier, or internal sensor failure), plan for possible transmission service or overhaul, especially if the vehicle has high mileage or other transmission symptoms.
RELATED CODES
- P0715: Input/Turbine Speed Sensor Circuit
- P0716: Input/Turbine Speed Sensor Range/Performance
- P0721: Output Speed Sensor Range/Performance
- P0722: Output Speed Sensor No Pulses
- P0700: Transmission Control System Malfunction
- P0740: Torque Converter Clutch Circuit Malfunction
Note: P0720 is often seen with related speed-sensor and transmission control codes. Investigate any accompanying codes to guide the repair path.
REPAIR OPTIONS AND COSTS (2025 ESTIMATES)
Prices vary by region, shop, and whether the vehicle is under warranty. These ranges are typical for consumer repairs and reflect both parts and labor.
A. OSS sensor replacement
- Parts: OSS sensor typically $20–$120 (OEM vs aftermarket).
- Labor: ~0.5–2.0 hours depending on access and service procedure.
- Estimated total: $100–$350.
- Notes: For some Durango layouts, sensor access is straightforward; in others, it may require removing nearby shields or components.
B. Wiring harness/connector repair
- Parts: Connectors, pins, heat-shrink, dielectric grease as needed ($10–$60).
- Labor: ~0.5–2.5 hours depending on accessibility and extent of wiring repair.
- Estimated total: $80–$350.
- Notes: If damage is extensive, harness replacement or repair may be more involved.
C. Transmission fluid service (if indicated)
- Fluid and filter change: $150–$300 (fluid cost + labor).
- Notes: This is a routine service that can help with ambiguous signals if the fluid is degraded, though it may not fix a true OSS fault.
D. PCM/TCM software update or reflash
- Parts: None (software only) if applicable.
- Labor/diagnostic: $100–$250 at a dealer or capable shop.
- Notes: Some updates may require dealer-level software access.
E. Internal transmission service (tone wheel, internal sensor, rebuild scenarios)
- Parts: Can be substantial; depends on damage.
- Labor: High; typically $1000–$4000+ depending on extent.
- Notes: This is a last-resort path if an internal component is faulty and OSS-related signals cannot be corrected externally.
F. Replacement timing (DIY component costs)
- If you’re replacing the OSS sensor yourself and you’re not changing the transmission fluid, total may stay near the lower end of the range (roughly $100–$250 including parts and basic tools). If you hire a shop or replace related harnesses, costs rise accordingly.
DIY vs PROFESSIONAL
- DIY feasibility (OSS sensor replacement): Moderate. If the sensor is accessible from the top or side of the trans and you’re comfortable with disconnecting wiring, removing clips, and re-torquing a sensor, this can be a doable weekend task. Expect to drain some ATF and to take safety precautions (vehicle on level ground, parking brake engaged, supports if wheels are off).
- Pros: Lower cost, quick turnaround, hands-on learning.
- Cons: Potential for incorrect torque, improper connector seating, or missing deeper wiring damage. If you’re not confident with transmission electronics, consider a professional.
- Professional route: Recommended if you’re not comfortable working near the transmission, if you suspect a tone wheel issue, or if the fault persists after a sensor replacement. A shop can perform live data monitoring, use scopes/automation to verify OSS integrity, and check for related codes without guesswork.
- When to seek professional help immediately: transmission slipping severe symptoms, any signs of fluid leak, steep trouble codes beyond P0720, or if the vehicle is in limp mode and you need reliable transportation.
PREVENTION
- Regular transmission service: Change ATF at recommended intervals with the correct spec for your Durango. Clean, fresh fluid helps maintain sensor performance and overall transmission health.
- Keep the OSS area clean and protected: Repair leaks promptly and wash away oil or grime from the sensor harness area to avoid signal contamination.
- Protect wiring: Ensure harness routes are not rubbing against hot surfaces or sharp edges. Use loom and protective tape where needed.
- Check connectors: Periodically inspect the OSS connector and other nearby connectors for corrosion or loose pins; apply dielectric grease when appropriate after cleaning.
- Software updates: When Dodge releases TCM/PCM software updates that address shift quality or sensor interpretation, consider applying them as directed.
- Drive habits: Smooth shifting and avoiding aggressive launches can reduce stress on the transmission sensors and tone wheel components over time.
- If you upgrade or modify the exhaust, engine intake, or drivetrain components, re-check sensor wiring routing and shielding to prevent new interference.
Final notes
- No recalls found in NHTSA database for this specific combination (2021–2024 Dodge Durango with P0720) and no official complaints listed in the provided data. This means there isn’t a dataset-supported, model-wide defect notice to rely on, so you should rely on standard diagnostic practices and current service information from Dodge or your trusted repair facility.
- Given the importance of the OSS signal to proper transmission operation, begin with a careful sensor/wiring inspection and testing. If in doubt, a professional diagnostic with live data logging is the most reliable path to a correct, lasting repair.