U1424 on 2016 Fiat 500X: Causes of Implausible Engine Torque Signal

What's Unique About the 2016-2016 Fiat 500X

For the 2016 Fiat 500X and its platform-mate, the Jeep Renegade, this code is exceptionally well-documented by the manufacturer. Fiat Chrysler Automobiles (FCA) released multiple Technical Service Bulletins (TSBs) specifically to address U1424. Unlike many other vehicles where this code might trigger a hunt for faulty sensors or wiring, on the 500X the problem is most often a logic issue within the PCM's original software. The official fix is a multi-module software reflash (PCM, TCM, BCM) to correct how the PCM interprets sensor data and communicates it to other modules.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light (Malfunction Indicator Lamp or MIL) is on
• "Drive Mode Not Available" message on the dash 🎬 Watch: See what the 'Drive Mode Not Available' warning looks like.board
• Harsh or erratic automatic transmission shifting
• Poor or delayed accelerator pedal response
• Engine RPM flare at startup
• Rough idle when shifting into Drive or Reverse
• Remote start may turn on and then shut off after a few seconds

Most Likely Causes

1. Outdated Powertrain Control Module (PCM) Software 🔴 High Probability → Shop Engine Control Module (ECM) The original software calibration on the 2.4L engine models was prone to misinterpreting sensor data, leading Fiat to issue multiple TSBs with an updated software fix. This is a known logic error from the factory.
   How to confirm: A dealer or a shop with a wiTECH scan tool can check the current PCM software calibration ID and compare it against the latest version specified in TSB 08-010-16 REV. D. The presence of U1424, especially with P0335, is a strong indicator.
   Typical fix: Reprogramming (flashing) the PCM, TCM (Transmission Control Module), and BCM (Body Control Module) to the latest available software versions as a complete package.
   Est. part cost: $0
2. Failing Crankshaft Position Sensor 🟡 Medium Probability → Shop Engine Crankshaft Position Sensor The TSBs consistently group code P0335 (Crankshaft Position Sensor Circuit) with U1424. A sensor providing erratic data due to heat soak or internal failure can cause the PCM to calculate and broadcast an implausible torque value.
   How to confirm: Scan for code P0335. If present and the software is already up to date, test the sensor's signal with an oscilloscope and check its wiring and connector for damage, especially for melting near the exhaust. A basic resistance test with a multimeter should show a value between 200 and 1,000 ohms, but an oscilloscope is better for finding intermittent issues.
   Typical fix: Replace the crankshaft position sensor and perform the crankshaft position relearn procedure if required. 🎬 See this walkthrough for the crankshaft position sensor location and replacement.
   Est. part cost: $30-$85
3. Weak or Failing Battery / Loose Terminal ⚪ Low Probability Modern vehicles with multiple electronic modules are sensitive to system voltage. A weak battery or poor connection can cause communication glitches between modules, leading to implausible data codes like U1424.
   How to confirm: Test the battery's health (voltage and load test) and check the charging system voltage. Physically inspect and tighten the battery terminals. A loose ground terminal has been reported by an owner to cause PCM communication failure that was misdiagnosed as a bad PCM. The main battery ground strap connects to the frame under the battery tray.
   Typical fix: Clean and tighten battery terminals or replace the battery if it fails a load test. If corroded, replace the main battery ground cable (OEM P/N 52104101). 🎬 Watch: How to replace a corroded main ground strap.
   Est. part cost: $0-$250

Diagnosis Steps

1. Connect a high-level OBD-II scanner capable of reading manufacturer-specific codes and software versions (e.g., wiTECH).
2. Scan all modules for DTCs. Note all codes present alongside U1424, paying close attention to P0335.
3. Check the current software calibration ID of the Powertrain Control Module (PCM).
4. Verify if the vehicle's VIN is covered by TSB #08-010-16 REV. D or any superseding bulletin.
5. If the software is outdated, the primary repair is to reprogram the PCM, TCM, and BCM to the latest software versions. A battery charger must be connected to maintain stable voltage (13.2-13.5V) during this process.
6. After the update, clear all DTCs, perform the proxy alignment procedure if prompted by the scan tool, and perform a test drive to confirm the fix.
7. If U1424 returns, or if P0335 was present and persists, begin diagnostics on the crankshaft position sensor circuit. Check the sensor's wiring, connector, and signal.
8. As a basic step, inspect and test the battery and charging system. Ensure battery terminals are clean and tight to rule out voltage-related communication issues. The main battery ground is located under the battery and its tray.

Parts You'll Likely Need

• Crankshaft Position Sensor (OEM #68079375AD) — This is the most likely hardware failure associated with U1424, especially if code P0335 is also present and a software update does not resolve the issue. This part supersedes previous versions 68079375AB and 68079375AC.
  Trusted brands: Mopar, Delphi, NGK, Walker Products
  OEM price range: $80-$120
  Aftermarket price range: $30-$60

Related Codes That Often Appear With This One

• P0335 — Crankshaft Position Sensor Circuit. This is the most common companion code. The PCM uses crank sensor data to calculate torque, so a fault here directly leads to an implausible torque signal. The TSBs address both codes simultaneously.
• P1185 — General Pressure Sensor Correlation. This indicates a conflict between various pressure sensors (like MAP, Barometric, etc.), which also impacts torque calculation. This code is also listed as being resolved by the TSB software update.
• P050D — Cold Start Rough Idle. This points to issues during the engine's warm-up phase, which the software update is also designed to correct.

Technical Service Bulletins (TSBs) & Recalls

• 08-010-16 REV. D
• 0801016
• 08-010-16 REV. C
• 08-010-16 REV. B
• 08-010-16
• 18-014-16 (Jeep Renegade)
• 18-081-19 (Jeep Renegade)

Platform-Specific Known Issues

• Fiat issued multiple revisions of Technical Service Bulletin #08-010-16 for the 2016 500X, with the latest being REV. D. This bulletin explicitly calls for a software update to the PCM, TCM, and BCM to resolve U1424 and a list of related codes and drivability symptoms.
• This issue is not unique to the Fiat 500X; its platform-mate, the Jeep Renegade (2015-2018) with the 2.4L engine, experiences the identical U1424/P0335 fault and has its own corresponding TSBs calling for a PCM software update.

Mechanic-Grade Diagnostic Values

• Crankshaft Position Sensor (CKP) Resistance — expected: 200 - 1,000 Ohms. Failure: An open circuit (infinite resistance) or a value significantly outside the expected range. However, a sensor can still be faulty even if resistance is within spec (intermittent failure), making an oscilloscope test more definitive.
• CAN C Bus Voltage (Key On, Engine Off) — expected: CAN High (Pin 6 at DLC): ~2.6V. CAN Low (Pin 14 at DLC): ~2.4V.. Failure: CAN High shorted to ground: ~0V. CAN Low shorted to ground: ~0V. CAN High shorted to 12V: ~12V. CAN Low shorted to 12V: ~12V. Both lines shorted together: Both lines will read ~2.5V but will be static. An open circuit will cause one line to read normal while the other may drift.
• System Voltage During Module Flashing — expected: 13.2V - 13.5V. Failure: Voltage dropping below 13.2V or climbing above 13.5V can cause the reprogramming process to fail and potentially damage the module.

Scan Tool Commands That Help

• wiTECH or equivalent (AlfaOBD, Appcar DiagFCA): Proxy Configuration Alignment — This procedure is required after reprogramming or replacing any module on the CAN bus (including the PCM, TCM, or BCM). It synchronizes the vehicle's configuration across all modules. A flashing odometer is a key indicator that a proxy alignment is needed.
• wiTECH or equivalent: Cam/Crank Relearn (also called Phonic Wheel Relearn) — This should be performed after replacing the crankshaft position sensor or after any work involving the timing components. It allows the PCM to learn the precise position of the new sensor relative to the crankshaft's reluctor wheel.
• wiTECH: Restore BCM/Vehicle Proxi Configuration — This is a preliminary step before a Proxy Alignment, used to ensure the BCM's stored configuration is correctly established before being copied to other modules.

Wiring & Ground Locations

• Main Battery Ground — The main ground strap from the battery negative terminal attaches to a stud on the vehicle's frame, located directly underneath the battery and battery tray.. A corroded or loose main ground is a well-documented cause of widespread communication errors, including U1424. It can cause voltage drops and noise on the network, leading to modules failing to communicate correctly. This is often misdiagnosed as a failed PCM.
• CAN C Bus at DLC — At the Data Link Connector (OBD-II port), CAN C High is on Pin 6 and CAN C Low is on Pin 14.. These are the primary diagnostic points for testing the integrity of the main communication network between the PCM, TCM, and ABS modules. Measuring voltage and resistance here can quickly identify network-wide shorts or open circuits.
• Crankshaft Position Sensor Wiring — The sensor wiring harness runs from the sensor (located on the bell housing between the engine and transmission) up towards the top of the engine.. This harness is susceptible to heat damage from the nearby exhaust system. If the wiring melts and shorts, it will cause a P0335 code and, consequently, the U1424 code.

Real Owner Repair Stories

• Reddit user on r/fiat500 (2016 Fiat 500X) — Multiple warning lights, communication failures.
  ❌ Tried (didn't work) Taking the vehicle to a dealership.
  ✅ What actually fixed it The dealership quoted $800 for a new PCM. The owner found the actual cause was a loose battery ground terminal. Tightening the terminal resolved all issues for $0.

OEM Part Supersession History

• 68079375AB, 68079375AC → 68079375AD — Improved design or manufacturing process to increase reliability and prevent premature failure that contributes to P0335 and related codes.