P0720 on 2005-2019 Nissan Frontier: Output Speed Sensor Causes and Fixes

What's Unique About the 2005-2019 Nissan Frontier

On this generation of Nissan Frontier, which uses the Jatco RE5R05A 5-speed automatic transmission, the P0720 code is notoriously deceptive. While the code points to the output speed sensor, the root cause is very frequently a failure of the Transmission Control Module (TCM) itself. On models from mid-2004 onwards, the TCM is integrated into the valve body inside the transmission pan, where it's exposed to heat and fluid. Additionally, 2005-2010 models are prone to an internal radiator failure that contaminates the transmission fluid with coolant (the 'strawberry milkshake of death' or SMOD), which can destroy the TCM and other internal electronics, triggering this code. A Nissan TSB for a similar 7-speed transmission (ITB19-040) explicitly states that if diagnosis for P0720 leads to the sensor, the technician should replace the control valve (TCM assembly) instead.

Symptoms You May Notice

• Check Engine Light is on
• Erratic, harsh, or delayed gear shifts
• Transmission stuck in 'limp mode' (usually 3rd or 5th gear)
• Speedometer works erratically or not at all
• Cruise control will not function
• Engine may hesitate or stall, especially when coming to a stop
• Decreased fuel economy
• Inability to shift out of Park

Most Likely Causes

1. Faulty Transmission Control Module (TCM) 🔴 High Probability → Shop Transmission Assembly On Nissan trucks with the RE5R05A transmission, the TCM is a known failure point. It is located inside the transmission on the valve body, where it is exposed to heat and potentially contaminated fluid, leading to internal electronic failure.
   How to confirm: This requires an advanced scan tool to monitor live data from the TCM and see if the output speed readings are erratic or nonsensical (e.g., showing 170mph when stopped), even after the sensor is replaced. If the sensor and wiring test good, the TCM is the likely culprit.
   Typical fix: The TCM, which is integrated with the valve body assembly, must be replaced. This involves draining the fluid, dropping the transmission pan, and replacing the entire unit. 🎬 Watch: Step-by-step guide to replacing the internal TCM and valve body Some remanufactured units come pre-programmed to the vehicle's VIN.
   Est. part cost: $300-$1200+
2. Contaminated Transmission Fluid (Coolant Intrusion) 🟡 Medium Probability → Shop Transmission Assembly On 2005-2010 models, the factory Calsonic radiator has a tendency to fail internally, leaking engine coolant into the integrated transmission cooler lines. This creates a pink, milky fluid ('strawberry milkshake' or SMOD) that ruins the transmission's electronics, including the TCM.
   How to confirm: Check the transmission fluid via the dipstick. If the fluid is pink, milky, or foamy, you have coolant contamination. Also check the coolant in the radiator/overflow for signs of transmission fluid.
   Typical fix: This is a major repair. The radiator must be replaced, the transmission and cooler lines must be thoroughly flushed multiple times, and the transmission (including the TCM and valve body) will likely need to be rebuilt or replaced.
   Est. part cost: $1500-$4000+
3. Faulty Output Speed Sensor (VSS) 🟡 Medium Probability
   How to confirm: The sensor can be tested with a multimeter for resistance and voltage output to see if it's within the manufacturer's specifications. Visually inspect it for damage or metal shavings. It is located on the exterior of the transmission's tail housing.
   Typical fix: Replace the sensor. It is typically located on the exterior of the transmission's tail housing and held in by a single 10mm bolt. 🎬 Watch: How to test and replace the output speed sensor
   Est. part cost: $30-$150
4. Damaged Wiring or Connectors ⚪ Low Probability
   How to confirm: Visually inspect the wiring harness leading to the output speed sensor for any signs of fraying, melting, corrosion, or loose pins at the connector. Perform a continuity test on the wires between the sensor and the TCM connector. Manufacturer Bulletin #NTB14019 notes that moisture or corrosion present on or around speed sensor pins can trigger P0720.
   Typical fix: Repair or replace the damaged section of the wiring harness or clean/replace the connector.
   Est. part cost: $10-$50

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) While the TCM is the more common failure point for transmission logic, the main engine computer (PCM) can also fail, though this is rare.
• Low or Burnt Transmission Fluid: → Shop Transmission Assembly Extremely low or degraded transmission fluid can cause a variety of shifting problems and codes, including P0720, due to improper hydraulic pressure and component lubrication.

Diagnosis Steps

1. Scan for Codes: Use an OBD-II scanner to confirm P0720 and check for any other related transmission codes like P0717 or P0500.
2. Check Transmission Fluid (CRITICAL STEP): For any 2005-2010 model, this is the most important first step. Check the fluid level and condition. If it is pink and milky (SMOD), the radiator has failed and the transmission is compromised. Stop diagnosis and address this first. 🎬 See how to perform a bypass to prevent SMOD damage If fluid is just low or burnt, top-off or change it.
3. Inspect Wiring and Connector: Visually inspect the wiring harness and connector for the output speed sensor, located on the rear of the transmission. Look for any obvious damage, corrosion, or loose connections.
4. Monitor Live Data: Use a capable scan tool to view the live data stream for the Output Shaft Speed. Observe the reading while driving. If the reading is erratic, drops to zero, or shows impossible speeds while the vehicle is moving steadily, it confirms a signal problem.
5. Test the Sensor: If the fluid and wiring look good, you can test the sensor itself. This usually involves checking its internal resistance with a multimeter and comparing it to factory specs.
6. Test the Circuit: Check for proper voltage and ground at the sensor connector. This confirms the circuit from the TCM to the sensor is intact.
7. Suspect the TCM: If the sensor and wiring have been tested and are confirmed to be good, but the live data is still erratic, the problem is most likely an internal failure of the Transmission Control Module (TCM). This is a very common failure on the Frontier and its platform mates.

Parts You'll Likely Need

• Transmission Control Module (TCM) / Valve Body Assembly (OEM #31705-X428E (example, VIN specific)) — This is the most frequent, though most expensive, cause of P0720 on this specific vehicle. It is integrated with the valve body inside the transmission. Part number is VIN-dependent.
  Trusted brands: Nissan (OEM), Hitachi, Street Smart Transmission (Remanufactured), Vertex (Remanufactured)
  OEM price range: $1000-$1500+
  Aftermarket price range: $400-$800 (Remanufactured)
• Output Speed Sensor / Vehicle Speed Sensor (VSS) (OEM #31935-8E007 (or superseding 31935-1XF00)) — This is the part the code directly points to and is a common failure item on many vehicles, though often misdiagnosed on the Frontier.
  Trusted brands: Nissan (OEM), Hitachi, NGK/NTK, JDMSPEED
  OEM price range: $100-$180
  Aftermarket price range: $30-$100
• Radiator (OEM #21460-EA215 (example, check for updated part)) — For 2005-2010 models, a failed radiator is the root cause of the 'strawberry milkshake of death' that destroys the transmission electronics. It's critical to replace with an updated part number if SMOD occurs.
  Trusted brands: Koyo, Spectra Premium, Denso, Nissan Value Advantage
  OEM price range: $300-$500
  Aftermarket price range: $150-$300

Related Codes That Often Appear With This One

• P0717 — This code is for the Input Speed Sensor. Since both sensors work together to monitor transmission operation, a major fault in the TCM or fluid can sometimes trigger codes for related components.
• P0500 — This code is for the Vehicle Speed Sensor (VSS) circuit, which often takes its reading from the same sensor as P0720. Seeing both codes together strongly points towards the sensor itself or its wiring, but a failing TCM can also cause it.

Technical Service Bulletins (TSBs) & Recalls

• ITB19-040 (Infiniti): While for a different transmission (RE7R01A), this TSB shows Nissan's official procedure for a P0720 code. It instructs technicians that if diagnosis points to the output speed sensor, they should replace the entire control valve (TCM assembly), not the sensor. This supports the common failure pattern seen in the Frontier's RE5R05A.
• Bulletin #NTB10150A: This manufacturer bulletin notes that for certain vehicles with DTC P0720 stored, the required action is to replace the transmission control valve assembly (valve body) and reprogram the TCM.
• Bulletin #NTB14019: This bulletin highlights that P0720 can be triggered when moisture and/or corrosion is present on or around the speed sensor pins, requiring moisture removal as part of the action plan.

Platform-Specific Known Issues

• High failure rate of the Transmission Control Module (TCM) for the RE5R05A transmission, leading to a P0720 code even when the sensor is good.
• Internal radiator failure on 2005-2010 models, causing coolant to contaminate the transmission fluid and destroy the transmission/TCM (SMOD).
• Owner confusion between the Output Speed Sensor (Revolution Sensor, for P0720) and the Vehicle Speed Sensor (for P0500), which can be separate parts.

Mechanic-Grade Diagnostic Values

• Output Shaft Revolution Sensor Bench Test — expected: A DC hertz signal should be present on pin 2 while turning the output shaft.. Failure: No signal or an erratic signal indicates a failed sensor.
• Transmission Temperature Sensor #1 (in sump) Resistance — expected: Approximately 6.5k ohms at 68°F (20°C).. Failure: Resistance significantly outside this range.
• Output Shaft Revolution Sensor Connector Test — expected: Apply 12 volts to pin 1 and ground to pin 3 of the green connector inside the pan.. Failure: This setup is for bench testing the sensor's signal output on pin 2.

Scan Tool Commands That Help

• Nissan CONSULT or compatible J2534 device: Accelerator Pedal Released Position Learning — Must be performed after the battery is disconnected or the TCM/ECM is replaced to learn the pedal's fully released position.
• Nissan CONSULT or compatible J2534 device: Throttle Valve Closed Position Learning — Required after battery disconnect or TCM/ECM replacement to learn the throttle body's closed position.
• Nissan CONSULT or compatible J2534 device: Idle Air Volume Learning — This procedure resets the idle strategy and must be performed after major electronic components like the TCM or ECM are replaced or disconnected.
• Nissan NERS (Nissan ECU Reprogramming Software): TCM Programming — When installing a new or non-programmed remanufactured TCM/Valve Body, this software is used with a J2534 pass-thru device to flash the correct VIN-specific calibration file to the module.

Wiring & Ground Locations

• Output Shaft Revolution Sensor Connector — Inside the transmission oil pan, it is a green connector that links the sensor to the main internal harness.. This is the direct connection point for the sensor. To bench test the sensor, you must drop the pan to access this connector and apply power/ground to its pins.
• Main External Transmission Harness Connector — On the passenger side of the transmission case. For models with the internal TCM (mid-2004+), this is a single large connector that passes all signals through the case.. This is the primary point to check for external wiring damage, corrosion, or a loose connection before assuming the fault is internal to the transmission.

Real Owner Repair Stories

• Reddit user on r/nissanfrontier (2014 Frontier SV 2WD, 105k miles) — Truck acted like it was stuck in gear, CEL on with code P0720. The issue would happen randomly once warmed up, typically at stop lights, and would resolve after restarting the engine. Shifting to neutral at stops or using manual shift mode prevented the issue.
  ❌ Tried (didn't work) Replacing the output speed sensor with a new OEM Nissan part.
  ✅ What actually fixed it The user did not post a final fix, but the symptoms (working after restart, OEM sensor not fixing it) are classic signs of a failing internal TCM, which other users in the thread suggested was the likely cause.
• Reddit user on r/q50 (similar 7AT transmission) (2015 Infiniti Q50) — P0720 code, car would not shift past 3rd gear and manual mode was disabled.
  ❌ Tried (didn't work) Replacing the valve body assembly., Replacing the output speed sensor.
  ✅ What actually fixed it The entire transmission had to be replaced, suggesting a deeper internal mechanical or hydraulic issue that was causing the speed sensor circuit fault.
• NHTSA ODI #11652917 — An owner reported entering limp mode on the highway and being unable to exceed 40 mph in a 70 mph zone, with a P0720 code that usually points to a valve body or transmission.
• NHTSA ODI #11683803 — An owner described a dangerous situation in traffic where the vehicle could not accelerate normally; a scan revealed a P0720 Speed Sensor Circuit failure, and the dealer advised replacing the valve body assembly.

OEM Part Supersession History

• 31935-8E007, 31935-8E005 → 31935-1XF00, 31935-1XF0C, 31935-1XF0D — Part has been updated multiple times by Nissan over the years.
  Heads up: While the latest part numbers are generally backward compatible, it is always critical to verify the correct part for your specific VIN. Aftermarket sensors often cross-reference all these numbers.

Model Year Variations Within This Range

• 2005-Mid 2007: Early RE5R05A transmissions may have used a Bosch-made TCM. Later models (approx. 2007 onwards) often have a Hitachi-made TCM.
• 2009+: The valve body was redesigned in 2009. Changes included the elimination of most pressure switches and temperature sensor #2, along with different TCM programming.
• Mid-2004 and earlier vs. Mid-2004 and later: The earliest versions of the RE5R05A (not typically in the Frontier D40 generation) had an external TCM located in the passenger kick panel. From mid-2004 on, all models moved to an internal TCM integrated with the valve body.

Diagnostic Flowchart

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A used output speed sensor is a low-risk purchase. For the main failure, the TCM/Valve Body assembly, a used part can be a cost-effective option ONLY if it is from a donor vehicle with documented low mileage and no history of transmission issues or SMOD. However, a professionally remanufactured unit is a safer bet.

Donor-vehicle mileage cap: roughly under 80000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Verify the donor vehicle's VIN to ensure TCM compatibility.
• Ask for the donor vehicle's mileage and history; avoid units from cars with high mileage or known transmission problems.
• Inspect the fluid from the donor transmission if possible. Any sign of coolant (pink/milky) or excessive metal shavings is a major red flag.
• When buying a valve body, confirm the part number on the TCM itself matches what is required for your vehicle, as they are not all interchangeable even if they look identical.

OEM-only on this vehicle (don't cheap out):

• Transmission Control Module (TCM) / Valve Body Assembly: Due to the high failure rate and VIN-specific programming, using a new OEM or a quality remanufactured unit with a warranty is strongly recommended over a junkyard part.

Aftermarket brands forum-validated for this vehicle:

• Street Smart Transmission (Remanufactured Valve Body)
• Vertex (Remanufactured Valve Body)
• Hitachi (OEM supplier for TCM and sensors)
• NGK/NTK (Sensors)

Brands owners have reported issues with on this vehicle:

• Unbranded, no-name electronic parts (sensors, TCMs) from online marketplaces, as their quality and programming are often questionable.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0717 — Input/Turbine Speed Sensor Circuit No Signal. This code is often checked for alongside P0720 as it relates to another critical transmission speed sensor. A failing TCM or widespread wiring issue could potentially affect both input and output sensor circuits.
• P0500 — Vehicle Speed Sensor (VSS) Malfunction. This code is related because a faulty VSS can cause similar symptoms like an inoperative speedometer and cruise control. Owners often confuse the VSS with the output speed sensor that triggers P0720.
• P0750 — Shift Solenoid 'A' Malfunction. This code is related because the primary causes for P0720—a faulty TCM or coolant-contaminated fluid (SMOD)—will also damage the shift solenoids, which are part of the same valve body assembly as the TCM.
• P0740 — Torque Converter Clutch Circuit Malfunction. Like shift solenoid codes, this is related because the TCC solenoid is located in the valve body and is highly susceptible to the same electronic (TCM) and fluid contamination (SMOD) failures that cause P0720.

Frequently Asked Questions