C0037 on 2018-2020 Jeep Compass: Left Rear Wheel Speed Sensor Fault Causes and Fixes

What's Unique About the 2018-2020 Jeep COMPASS

The second-generation Jeep Compass (MP/552 platform) has well-documented issues with its wheel speed sensors. FCA (Jeep's parent company) has issued Technical Service Bulletin (TSB) 05-003-21 acknowledging that water intrusion and oxidation can cause these sensors to fail, leading to codes like C0037. [69, Bulletin #0500321] This TSB explicitly recommends replacing all four wheel speed sensors as a preventative measure. Another service document points to potential damage or corrosion in the wiring harness leading to the sensor as a common point of failure. This suggests the problem is often with the sensor or its immediate wiring rather than a more complex system failure, a pattern confirmed by owner experiences.

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.
• Traction Control or Electronic Stability Control (ESC) light is on.
• "Service ABS System" or similar message on the instrument cluster.
• "Service Hill Start" message may appear.
• 4WD system warning light may illuminate.
• Cruise control is disabled or non-functional.

Most Likely Causes

1. Faulty Left Rear Wheel Speed Sensor 🔴 High Probability → Shop ABS Wheel Speed Sensor A manufacturer TSB (05-003-21) specifically mentions that oxidation or water intrusion into the sensor is a primary cause for these DTCs, recommending replacement of all four sensors. [69, Bulletin #0500321] Corrosion can build up in the sensor bore, physically squeezing and damaging the sensor itself.
   How to confirm: Use an ABS-capable scan tool to monitor live data from all four wheel speed sensors while driving. If the left rear sensor shows 0 MPH or an erratic reading while the others read correctly, the sensor has failed.
   Typical fix: Replace the left rear wheel speed sensor. 🎬 Watch this step-by-step guide to fixing the C0037-62 fault code. The original OEM part number 68430135AA has been superseded by 68563837AA. Due to the high failure rate from water intrusion, the TSB recommends replacing all four sensors at the same time.
   Est. part cost: $25-$75
2. Damaged Wiring or Connector 🟡 Medium Probability The wiring harness is exposed to road debris and moisture, and the constant movement of the suspension can cause wires to chafe or break over time, even inside the protective loom. An FCA service document specifically highlights inspecting and repairing the wheel speed sensor circuits for damage and corrosion.
   How to confirm: Visually inspect the wiring harness from the sensor to where it enters the vehicle body. Check for chafing, breaks, or green/white corrosion in the connector. A known failure point is an internal wire break that is not visible externally, requiring continuity testing or harness manipulation 🎬 Watch a deep dive into testing the wheel speed sensor circuit. while watching live data.
   Typical fix: Repair the damaged section of wire or replace the connector pigtail. Splicing these wires is not recommended as it can introduce resistance and lead to future failures; replacing the harness section is the preferred repair.
   Est. part cost: $15-$50
3. Damaged or Debris-Covered Tone Ring ⚪ Low Probability The tone ring, which the sensor reads, is part of the wheel bearing/hub assembly. While less common, rust buildup or physical damage from road debris can interfere with the sensor's reading. A YouTube video by South Main Auto Repair on a similar Jeep Compass issue showed that a faulty new wheel bearing with a defective tone ring 🎬 See how a pro diagnoses a tricky ABS light after driving. can also cause these codes.
   How to confirm: After removing the wheel speed sensor, visually inspect the tone ring inside the hub for rust, debris, or broken teeth. Spin the hub and watch the live data on a scan tool to look for signal dropouts.
   Typical fix: Clean the tone ring if it's just dirty. If the ring is damaged, the entire wheel bearing/hub assembly must be replaced as the tone ring is integrated.
   Est. part cost: $100-$250

Rare But Worth Checking

• Faulty ABS Control Module: → Shop ABS Control Module This is very rare and should only be considered after the sensor, wiring, and tone ring have all been confirmed to be in good condition. It is an expensive last resort.

Diagnosis Steps

1. Connect an ABS-capable scan tool and confirm C0037 is the active code. Note any sub-codes (e.g., -1D, -62, -2F).
2. View the live data stream for all four wheel speed sensors. Drive the vehicle slowly (under 10 mph) and observe the readings. The left rear should be different from the others (e.g., stuck at 0 or erratic).
3. Raise the rear of the vehicle and secure it on jack stands. Visually inspect the left rear wheel speed sensor wiring harness for any signs of physical damage, chafing, or corrosion at the connector. Wiggle the harness while monitoring live data to check for intermittent faults.
4. Remove the sensor (typically held by a single Allen bolt) and inspect it and the wheel hub's tone ring for debris, rust, or damage. Also inspect the sensor bore for corrosion that could be crushing the sensor.
5. If the wiring and tone ring look good, the sensor itself is the most likely culprit. Replace the left rear wheel speed sensor. Per TSB 05-003-21, consider replacing all four sensors to prevent future failures.
6. If a new sensor does not resolve the issue, perform a continuity test on the wiring harness between the sensor connector and the ABS module connector. Check for breaks, shorts to power, or shorts to ground. Remember that damage can be hidden under the harness tape.
7. If all tests pass, the issue may lie with the ABS control module, but this is rare and professional diagnosis is strongly recommended at this point.

Parts You'll Likely Need

• Rear Wheel Speed Sensor (OEM #68563837AA (supersedes 68430135AA)) — This is the most common failure point for code C0037, as identified by owner experiences and manufacturer TSBs citing failure from water intrusion. [69, Bulletin #0500321, 9]
  Trusted brands: Mopar, Duralast, Carquest Premium, A-Premium
  OEM price range: $30-$60
  Aftermarket price range: $20-$50

Related Codes That Often Appear With This One

• C003A — This is the code for the Right Rear Wheel Speed Sensor. TSB 05-003-21 groups these codes, suggesting a common failure pattern (like water intrusion) can affect both rear sensors. [69, Bulletin #0500321]
• C0031 — This is the code for the Left Front Wheel Speed Sensor. A TSB from Jeep lists all four wheel speed sensor codes together, indicating a potential systemic issue that could cause multiple sensors to fail. [69, Bulletin #0500321]
• C0034 — This is the code for the Right Front Wheel Speed Sensor, also listed in the same TSB as C0037. [69, Bulletin #0500321]
• U0418 — This code indicates 'Invalid Data Received From Brake System Control Module'. A fault in a primary input like a wheel speed sensor can cause the ABS module to send invalid data to other vehicle systems, triggering this communication code.

Technical Service Bulletins (TSBs) & Recalls

• 05-003-21 (supersedes 05-001-20): Addresses multiple wheel speed sensor codes, including C0037, caused by oxidation or water intrusion into the sensor. Recommends replacing all four sensors. [69, Bulletin #0500321]
• 0500120: Earlier version of the TSB, also pointing to electrical failures and invalid signals from the wheel speed sensors. [Bulletin #0500120]
• S2005000003: An internal service document advising inspection of the wiring harness for corrosion and damage when C0037-1D is present.

Platform-Specific Known Issues

• TSB #05-003-21 specifically addresses DTCs including C0037-1D, C0037-62, and C0037-2F on 2018-2019 (M6) and 2018-2020 (M1) Jeep Compass models. The bulletin states the cause is oxidation or water intrusion into the sensor and recommends replacing all four wheel speed sensors.
• A related FCA service document (S2005000003) for codes C0037-1D and C003A-1D advises technicians to inspect the wheel speed sensor circuits and wiring for damage and corrosion, even under the convoluted tubing, indicating wiring harness issues are a known problem.
• Owner experiences confirm that wiring can fail intermittently or break inside the protective loom, making visual diagnosis difficult without unwrapping the harness.

Mechanic-Grade Diagnostic Values

• Active Sensor Voltage Drop (Signal) — expected: A clean digital square wave that fluctuates by 0.1V to 1.0V when the wheel is spun. On a similar Jeep, a fluctuation of ~390mV (0.39V) was observed.. Failure: No waveform, a noisy/erratic waveform, or a flat line indicates a bad sensor or wiring issue.
• Sensor Supply Voltage (KOEO) — expected: Approximately 10-12 volts on the supply pin at the sensor connector with the key on, engine off.. Failure: Significantly lower voltage or no voltage points to a wiring problem between the ABS module and the sensor.

Hidden / Shadow Codes Worth Checking

• C0037-1D: Left Rear Wheel Speed Sensor - Circuit Current Out of Range. This indicates the current draw is outside the expected 7mA to 14mA range of an active sensor. (see via Standard ABS-capable scan tool. Listed in TSB 05-003-21 for M1/M6 vehicles.)
• C0037-62: Left Rear Wheel Speed Sensor - Signal Compare Failure. The ABS module compared the signal from this sensor to the other three and found a major discrepancy. (see via Standard ABS-capable scan tool. Listed in TSB 05-003-21 for M1/M6 vehicles.)
• C0037-2F: Left Rear Wheel Speed Sensor - Signal Erratic. The signal is momentarily implausible or discontinuous. (see via Standard ABS-capable scan tool. Listed in TSB 05-003-21 for M1/M6 vehicles.)
• C0037-01: Left rear speed sensor - General electrical failure. (see via Standard ABS-capable scan tool. Listed in TSB 05-001-20 for B1 platform vehicles. [Bulletin #0500120])

Scan Tool Commands That Help

• wiTECH or equivalent: ABS Module Reprogramming — If a TSB indicates that a software update is available to correct ABS-related symptoms. TSB 08-083-24 REV. A is an example of a bulletin that requires this procedure for the Compass, confirming its use as a repair path.
• ABS-capable Scan Tool: Live Data Graphing — This is the primary diagnostic step. Graphing all four wheel speeds simultaneously while driving makes it easy to spot which sensor is dropping out, reading zero, or providing an erratic signal compared to the others.

Wiring & Ground Locations

• Security Gateway Module (SGW) — Located under the dashboard, near the steering column. It is a small black module with two connectors.. For 2018+ models, an aftermarket scan tool cannot perform diagnostic functions (like clearing codes or viewing live data) without first bypassing this module. A specific SGW bypass cable is required to connect the scanner.
• ABS Module — Typically located in the engine bay, attached to the hydraulic control unit, often below or near the master cylinder and brake fluid reservoir.. This is the control unit that receives the sensor signal and sets the C0037 code. The wiring harness from the sensor ultimately terminates at this module's main connector.
• Probable ABS Ground (G107) — On similar Jeep platforms (WJ), the dedicated ABS ground is on the driver's side inner fender, behind the airbox. This is a high-probability location to inspect for corrosion or looseness on the Compass.. A poor ground for the ABS module can cause a host of erratic electrical issues and fault codes, including incorrect sensor readings.

Real Owner Repair Stories

• Pine Hollow Auto Diagnostics (YouTube) (Jeep Patriot (similar platform and sensor design)) — Persistent ABS sensor circuit code after parts had been replaced.
  ❌ Tried (didn't work) Replacing the wheel speed sensor.
  ✅ What actually fixed it The technician found an open circuit (broken wire) inside the wiring harness. The break was located between the firewall and a connector in the fender well and was not visible from the outside. The fix involved cutting out the damaged section of wire and soldering in a new piece with adhesive-lined heat shrink tubing to ensure a sealed repair.

OEM Part Supersession History

• 68430135AA, 68351461AA, 68351461AB → 68563837AA — Part revision and consolidation by the manufacturer. The same part number is used for both rear positions (left and right).

Model Year Variations Within This Range

• 2018-2020: TSB 05-003-21 distinguishes between different vehicle production codes. 'M1' refers to the standard Jeep Compass, while 'M6' refers to Compass models built for LATAM and APAC markets. The specific sub-codes that trigger the TSB can vary between these versions.
• 2018-2020: The same TSB (05-003-21) for 'M1' vehicles only applies to those built before a specific date that are NOT equipped with Parallel Park Assist (XAU) or Adaptive Cruise Control (NHZ), indicating the sensors or system logic may differ on higher-trim models.