C0513 on 2016 Fiat 500X: Right Rear Wheel Speed Rationality Fault Guide

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

For the 2016 Fiat 500X, this code is specifically called out in manufacturer service bulletins that point towards a software calibration issue within the ABS module. This can cause false rationality codes to be set. This is a critical distinction from simply having a bad sensor, as the first diagnostic step should be to check if the vehicle's control modules have the latest software updates. The TSB involves flashing the PCM, BCM, and TCM, indicating a complex system-wide logic update, not just an ABS module tweak. This issue is also known to affect its platform-mate, the Jeep Renegade.

Diagnostic Flowchart

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

Symptoms You May Notice

• ABS warning light is on
• Electronic Stability Control (ESC) or traction control warning light is on
• "ESC Off" message may appear on the dash
• Hill Holder system may be unavailable
• All-Wheel Drive (AWD) system may be disabled or show a warning, if equipped
• Cruise control may be inoperative
🎬 Watch: How to fix multiple dashboard warning lights easily

Most Likely Causes

1. ABS Control Module Software Requires Update 🔴 High Probability → Shop ABS Control Module Manufacturer TSB #08-010-16 REV. D specifically lists C0513 as a code that can be resolved by updating the software for the BCM, PCM, and TCM modules to improve diagnostic logic and prevent overly sensitive fault triggers.
   How to confirm: A dealer or a shop with a Fiat-compatible (wiTECH) scan tool can check the current software version against the latest available version specified in the TSB. They can also check the vehicle's VIN to see if it's covered under the associated Rapid Response Transmittal (RRT) 16-012.
   Typical fix: Reprogram the BCM, PCM, and TCM with the latest software. A battery charger must be connected during the flash process to maintain stable voltage.
   Est. part cost: $0
2. Faulty Right Rear Wheel Speed Sensor 🟡 Medium Probability → Shop ABS Wheel Speed Sensor Wheel speed sensors are exposed to road debris, water, and temperature extremes, which can lead to internal electronic failure or physical damage over time.
   How to confirm: Use a scan tool to monitor live data from all four wheel speed sensors while driving. The right rear sensor's reading will be erratic, drop to zero, not appear at all, or not match the other sensors' speeds. A visual inspection may reveal a cracked or damaged sensor.
   Typical fix: Replace the right rear wheel speed sensor. This involves removing the wheel, unbolting the sensor from the knuckle, and disconnecting its electrical connector. 🎬 See this step-by-step guide for replacing the ABS sensor
   Est. part cost: $70-$100
3. Damaged Wiring or Connector ⚪ Low Probability The wiring harness to the wheel speed sensor is routed in the wheel well and can be damaged by road debris, improper routing after previous repairs, or corrosion in the connector pins from moisture intrusion.
   How to confirm: Visually inspect the wiring from the sensor to the main harness for chafing, breaks, or pinch points. Unplug the connector and check for green or white corrosion on the pins. Check for continuity and shorts with a multimeter between the sensor connector and the ABS module.
   Typical fix: Repair the damaged wire or clean/replace the connector.
   Est. part cost: $5-$30

Rare But Worth Checking

• Damaged Tone Ring / Wheel Bearing Assembly: The tone ring (or magnetic encoder), which the sensor reads, is integrated into the rear wheel bearing/hub assembly on the Fiat 500X. A worn or failing wheel bearing can cause excessive play, leading to an erratic signal. The tone ring can also accumulate metallic debris or crack, which will disrupt the sensor's reading. This is often accompanied by a grinding or humming noise from the rear of the vehicle that changes with speed.
• Faulty ABS Control Module: → Shop ABS Control Module While rare, the ABS module itself can fail internally due to flash memory corruption or component degradation. This should only be considered after all other possibilities, including the software update, sensor, wiring, and wheel bearing, have been thoroughly ruled out.

Diagnosis Steps

1. Check for Technical Service Bulletins (TSBs). Specifically, verify if TSB #08-010-16 REV. D has been performed using a dealer tool or by calling a dealership with your VIN. If not, this is the primary recommended action.
2. Connect a diagnostic scan tool capable of reading ABS codes and live data from all modules.
3. Observe the wheel speed sensor data for all four wheels while driving. Confirm that the right rear sensor provides an erratic, dropping, or inconsistent reading compared to the others.
4. If the signal is faulty, perform a visual inspection of the right rear wheel speed sensor, its connector, and wiring for any signs of damage, corrosion, or looseness.
5. Inspect the wheel bearing for excessive play by grabbing the wheel at the 12 and 6 o'clock positions and trying to rock it. Any significant movement could indicate a bad bearing, which contains the tone ring.
6. If the wiring and bearing seem okay, the wheel speed sensor is the most likely failed component and should be replaced.
7. After replacement, clear the codes and test drive. If the code returns, test the wiring harness for continuity and for shorts to power or ground between the sensor and the ABS module.
8. If all other components test good and the software is up to date, the issue may be with the ABS control module itself, but this is the least common cause and should be the final diagnostic step.

Parts You'll Likely Need

• Rear ABS Wheel Speed Sensor (OEM #68372700AA, 51940921, 52017671) — This sensor is the most common hardware component to fail, causing an irrational signal reading.
  Trusted brands: Mopar, Standard Motor Products (ALS2819), Holstein, A-Premium (APABS0835)
  OEM price range: $99.97
  Aftermarket price range: $20-$90

Related Codes That Often Appear With This One

• C0507 — This is the rationality code for the Right Front wheel speed sensor. TSB #08-010-16 lists these codes together, suggesting the software issue can affect multiple sensors simultaneously.
• C050D — This is the rationality code for the Left Rear wheel speed sensor, also mentioned in the same TSB.
• C0501 — This is the rationality code for the Left Front wheel speed sensor, also listed in TSB #08-010-16. It's common for multiple or all four rationality codes to be set by the software glitch.
• U0428-00 — This code for 'Implausible Data Received From Steering Angle Sensor Module' is also listed in TSB #08-010-16, indicating a broader system communication or software calibration issue that the update is designed to fix.

Technical Service Bulletins (TSBs) & Recalls

• 08-010-16 REV. D: Flash: Diagnostic And System Improvements. This bulletin involves updating the BCM, PCM, and TCM with the latest software to address various DTCs, including C0513. It was also released as Rapid Response Transmittal (RRT) 16-012.

Platform-Specific Known Issues

• The 2016 Fiat 500X is subject to Technical Service Bulletin #08-010-16 REV. D, which indicates that 'Wheel Speed Signal Rationality' codes like C0513 can be caused by a software issue. The fix involves updating the Body Control Module (BCM), Powertrain Control Module (PCM), and Transmission Control Module (TCM) to the latest software version.

Mechanic-Grade Diagnostic Values

• Wheel Speed Sensor Resistance (Comparative) — expected: The resistance value (typically in the Mega-Ohm range) should be nearly identical to the sensor on the opposite side of the vehicle (e.g., left rear).. Failure: A reading of 'OL' (Open Loop) indicates an open circuit in the sensor, or a significant deviation from the known good sensor on the other side.
• Sensor Harness Wiring Continuity — expected: Less than 1.0 Ω of resistance between the sensor connector pin and the corresponding pin at the ABS module connector.. Failure: Resistance greater than 1.0 Ω indicates excessive resistance in the wire. A reading of 'OL' indicates a broken wire.
• Sensor Harness Wiring Short to Ground/Power — expected: Infinite resistance (OL) when testing between a signal wire and chassis ground or a known power source.. Failure: Any continuity or resistance reading indicates a short circuit in the harness.

Scan Tool Commands That Help

• MultiEcuScan, wiTECH, high-end Snap-on/Autel: Proxi Alignment (or Proxy Configuration) — This procedure is mandatory after replacing a major control module like the ABS module, Body Control Module (BCM), or Instrument Panel Cluster (IPC). It allows the new module to be recognized by all other modules on the vehicle's CAN network. Failure to perform a Proxi Alignment after module replacement can cause communication errors and persistent fault codes.

Wiring & Ground Locations

• Rear Wheel Speed Sensor Connector — Located in the rear right wheel well, connecting the sensor pigtail to the main chassis harness.. This 2-pin connector is a common point for corrosion or physical damage due to its exposed location, which can interrupt the signal from the sensor.
• Main Vehicle Ground Strap — On many Fiat models, a critical ground strap runs from the negative battery terminal area to a stud on the gearbox/transmission case.. While not specific to C0513, a corroded or loose main ground can cause a host of intermittent and difficult-to-diagnose electrical issues across various modules, including the ABS system. It should be inspected as part of any electrical diagnosis.

"I Checked Everything" — The Actual Cause

• A common scenario for this code is when the wheel speed sensor itself tests good for resistance, and the wiring shows perfect continuity with no shorts, yet the code persists. The actual cause is often a fault with the magnetic encoder ring that is integrated into the wheel bearing/hub assembly. The ring may have a hairline crack or have accumulated metallic debris, corrupting the signal it sends to the sensor. This is especially tricky because the wheel bearing may not be making any noise yet, leading technicians to overlook it.

OEM Part Supersession History

• 68246762AA, 68273185AA → 68372700AA — Part has been updated by the manufacturer. Superseded parts are no longer available from the OEM.