EN

Severity: Moderate Code type: Generic (all makes)

U0402 Code: Invalid Data Received From TCM "A"

The transmission module is online, but the gear, range or torque data it sends doesn't add up.

At a glance

Severity: 3/5 – Moderate3/5

Severity: Moderate

Meaning
Invalid Data Received From TCM "A"
System
Module Communication · Network
Safe to drive?
With caution
Typical repair cost
$40–$1,500
DIY difficulty
Moderate

U0402 is set by the PCM, ABS module, instrument cluster or shifter module when messages from the transmission control module (TCM) arrive on time but carry values that fail a plausibility check or are flagged invalid. Typical examples are a selected range that doesn't match the shifter, an attained gear that jumps around, an output speed that disagrees with wheel speed, or a torque-reduction request out of range. The TCM usually marks its own data invalid when it has an internal transmission fault such as a range sensor or speed sensor problem, so reading the TCM's codes comes first. Other classic triggers are a new or rebuilt TCM or valve body that wasn't programmed and adapted, and PCM/TCM software levels that don't match after only one module was updated.

Can I keep driving? The car usually drives, but shifting may be harsh, cruise and start-stop may be disabled and some cars refuse to start if Park or Neutral can't be confirmed. Don't rely on the gear display to know you're in Park; always set the parking brake until it's fixed.

How to read U0402

How to read U0402U10243024
  1. U Network
  2. 0 Generic (SAE)
  3. 4 Module Communication
  4. 02 Specific fault

Symptoms

  • Gear indicator blank, flashing or showing the wrong position
  • Harsh engagement into Drive or Reverse, or late, firm upshifts
  • Cruise control, auto start-stop or remote start stop working
  • Engine sometimes won't crank because Park/Neutral isn't confirmed
  • Transmission warning or check engine light, often with TCM codes
  • Speedometer or trip data glitching on models that use TCM output speed

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. Internal transmission fault reported by the TCM, e.g. range sensor or input/output speed sensor, making the TCM flag its data invalid 30%
  2. TCM or valve body replaced or rebuilt without programming, configuration and adaptive relearn 22%
  3. Software levels of PCM and TCM don't match after only one module was updated 15%
  4. Low voltage or a voltage spike (jump start, weak battery) during start-up 13%
  5. Shift cable or range sensor out of adjustment so the reported range disagrees with the lever 12%
  6. Internal TCM electronic fault 8%

Diagnosis step by step

Diagnostic flow: U04021Read the TCM's own codes2Compare displayed and actual range3Check shift cable and range sensoradjustment4Check software and repair history5Test the battery and crankingvoltage6Retest on a road test

  1. Read the TCM's own codes

    Open the transmission module directly with a capable scan tool. Range sensor, speed sensor, solenoid or internal-temperature codes in the TCM explain why it tags its outputs as invalid; repair those first and U0402 usually follows.

    Tools: OBD-II scanner

  2. Compare displayed and actual range

    With the engine running and your foot on the brake, move through P, R, N, D and each manual position while watching the TCM's range data. The reading should change cleanly at each detent with no in-between or 'invalid' values.

    Tools: OBD-II scanner

  3. Check shift cable and range sensor adjustment

    On cars with a mechanical selector, confirm the cable isn't stretched, the bushing at the transmission lever isn't worn and the range sensor is set to spec. A worn cable bushing lets the lever and the sensor disagree.

    Tools: Flashlight, Screwdriver

  4. Check software and repair history

    Ask whether the TCM, valve body or whole transmission was replaced or rebuilt, and compare PCM and TCM software with the latest release. Program both modules to matching levels and run the manufacturer's adaptive or quick-learn procedure afterward.

    Tools: OBD-II scanner

  5. Test the battery and cranking voltage

    Rest voltage should be near 12.6 V and cranking voltage above about 9.6 V. If U0402 is only stored as history after cold starts or a jump start, fix the battery before anything else.

    Tools: Multimeter

  6. Retest on a road test

    Clear codes, then drive through all gears including a few coast-downs and a reverse engagement. If U0402 returns with no TCM faults, correct software and good power, the TCM itself is suspect.

    Tools: OBD-II scanner

Where the parts are

Charging system and control modules – U04021234567
Charging system and control modules
  1. 1Battery
  2. 2Alternator
  3. 3Engine computer (ECM)
  4. 4CAN bus
  5. 5Transmission
  6. 6Wheel speed sensor
  7. 7High-voltage battery

Repair options & costs

RepairDIY?Estimated cost
Adjust shift cable or replace cable bushing Yes $40–$250
Replace transmission range sensor No $180–$600
TCM/PCM software update and adaptive relearn No $120–$300
Replace and program TCM No $500–$1,500

Rough US estimates for parts and labor; shop rates vary by region. Not a quote.

Notes by brand

Field data

Jeep 14 Cherokee, Renegade
Ram 4 1500, 3500
Chrysler 2 200, 300
Dodge 2 Caliber
Honda 2 Hr-V

Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.

Emissions / smog test impact

Depends

If the TCM also requests the check engine light (P0700 or a range sensor code), an OBD-based emissions test will fail. U0402 alone, stored only in a non-emissions module, usually doesn't light the lamp.

Frequently asked questions

Is U0402 the same as U0101?

No. U0101 means the transmission module stopped communicating. With U0402 it still communicates, but its gear, range or torque values are implausible, which usually points to a transmission-side sensor fault or a programming issue.

My transmission was just rebuilt and now I have U0402. Why?

A replacement TCM, valve body or transmission often needs programming, configuration and an adaptive relearn with a dealer-level scan tool. Until that's done, the TCM can send data the PCM doesn't accept.

Why won't my car start sometimes with this code?

The starter is only enabled when Park or Neutral is confirmed. If the PCM can't trust the range data from the TCM, it may refuse to crank. Moving the lever or cycling to Neutral sometimes helps temporarily.

Can I clear U0402 and keep driving?

You can clear it, but if the cause is a range sensor or cable problem the car may not know it is in Park. Set the parking brake every time and have it diagnosed soon.

Sources