2021-2022 Hyundai Transaxle Speed Sensor DTCs P071700, P072100, P072200

Symptoms of Automatic Transaxle Speed Sensor Issues

Owners of affected 2021-2022 Hyundai vehicles may notice a "Check Engine" light illuminated on their dashboard. This warning light indicates a potential issue with the automatic transaxle input/output speed sensor, which can lead to various transmission performance problems. For instance, if your Hyundai Tucson P071700 code is present, it points directly to a low input signal from the input/turbine speed sensor.

Fault Codes / DTCs

Hyundai TSB 22-AT-006H specifically identifies the following Diagnostic Trouble Codes (DTCs) related to the automatic transaxle input/output speed sensor:

DTC Code	Description
P071700	Input/Turbine speed sensor A circuit low input
P072100	Output speed sensor A circuit range/performance
P072200	Output speed sensor A circuit no signal

Diagnosis Procedure

To diagnose the issue, a technician will connect a GDS (Global Diagnostic System) tool to the vehicle. The initial steps involve recording any present DTCs and then clearing them. Following this, the technician will access the GDS Data Analysis menu to monitor the input and output speed sensor readings.

If the sensors show continuous and changing output while driving, it indicates that the wiring does not have open or short circuits. However, if there is no continuous or changing output, a visual inspection of the wiring harness between the Powertrain Control Module (PCM) or Transmission Control Unit (TCU) and the transmission is necessary. This inspection checks for damaged wires, open/short circuits, or improperly inserted pins in the connector. It's important to note that some models, like the Sonata (DN8a) and Palisade (LX2), utilize separate ECU and TCU units, while others have an integrated PCM.

Repair Procedure Summary

Hyundai TSB 22-AT-006H outlines a comprehensive repair procedure to address the automatic transaxle input/output speed sensor issue. This TSB supersedes TSB 20-AT-003H, adding the Tucson (NX4/NX4a) and Santa Cruz (NXT) models to its scope. The primary repair involves replacing the affected input/output speed sensor and the valve body harness.

The repair process begins by preparing the vehicle, which includes recording radio presets, removing the air cleaner, battery, and battery tray. The vehicle is then lifted, and the undercover is removed. Depending on access requirements, the radiator may need to be drained, and the lower radiator hose removed, followed by draining the Automatic Transmission Fluid (ATF).

Next, the harness is disconnected from the transmission, and the bolt securing the retainer is removed to push the harness connector inward. The vent hose on the oil pan is disconnected, and the 14 oil pan bolts are removed to detach the oil pan. Technicians must carefully remove bolts securing the harness and oil temperature sensor, followed by the detent spring bolt. The valve body is then removed by detaching its nine bolts, ensuring it is placed on a clean paper towel to prevent lint contamination.

The old input/output speed sensor and harness are removed and replaced with new components. After confirming the correct installation of O-rings, the valve body is reinstalled, aligning the manual shaft to the shift lever. All bolts are reinstalled and torqued to specification, including the valve body bolts (7-9 lb.ft), detent spring bolt (8-11 lb.ft), and harness/oil temperature sensor bolts (7-9 lb.ft).

A new gasket is installed on the oil pan, and the pan is reinstalled with its 14 bolts torqued to 6-7 lb.ft. The lower radiator hose is reattached, and ethylene glycol engine coolant is added. After reconnecting the battery and inputting radio presets, the transaxle is refilled with approximately 5-6 quarts of SP4-M ATF. The ATF level is checked using the GDS, ensuring the fluid temperature is between 122-140°F (50-60°C) with the engine running and the shift lever in "P".

Finally, the DTCs are cleared, and the vehicle is test-driven for two key-on/key-off driving cycles, including full upshifts and downshifts. If the DTCs, such as the Hyundai Tucson P071700, return after the test drive, the PCM or TCU may need to be replaced, depending on the vehicle's configuration.

Required Parts

To perform this repair, the following parts are needed:

• Input/Output Speed Sensor: PNC 42620, Part No. 42620-4G***
• Valve Body Harness: PNC 46307, Part No. 46307-4G***
• Oil Pan Gasket: PNC 45282E, Part No. 45283-4G***
• SP4-M ATF

Warranty Information

This repair is covered under warranty using the following codes:

• Operation Codes: 45644R00, 45644R8M, 45644R8L, 45644RQ0
• Causal Part: 13A
• Cause Code: ZZ3

Important Warnings for Technicians and Owners

• When removing the oil pan, "Use a rubber hammer to tap the oil pan cover on a corner until the cover is loose."
• When handling the valve body, "Place the valve body on a clean paper towel. Placing the valve body on a rag may cause lint to enter the valve body."
• "All listed vehicles have a PCM (integrated ECU/TCU) except Sonata (DN8a) and Palisade (LX2) with separate ECU and TCU." This distinction is crucial for proper diagnosis and potential component replacement.

Source: NHTSA TSB ID 10213720