C1625 – CAN timeout – ABS/ESC (Hyundai)

C1625 means your 2019 Hyundai Kona lost communication with the ABS/ESC system long enough to set a fault. In plain English, the car may disable stability control and sometimes ABS as a safety fallback. You may also see warning lights and reduced traction support. According to Hyundai factory diagnostic data, this is a Hyundai-defined chassis code meaning “CAN timeout – ABS/ESC.” That definition can vary by platform details, so you must confirm which module logged it and which CAN messages timed out before you replace anything.

C1625 Quick Answer

C1625 on Hyundai indicates a CAN network timeout involving the ABS/ESC module. Diagnose it as a communication fault first: power/ground, connectors, CAN wiring integrity, and network-wide scan results come before any module replacement.

What Does C1625 Mean?

Official definition (Hyundai): “CAN timeout – ABS/ESC.” The logging module expected ABS/ESC data over the CAN network and did not receive it within the allowed time. In practice, the vehicle may turn on ABS, ESC, or traction warnings and reduce stability functions because it cannot trust missing chassis data.

What the module checks and why it matters: A Hyundai controller monitors specific ABS/ESC CAN messages for presence and freshness. It does not “see” the ABS pump or wheel sensors directly when this code sets. It only sees missing or stale network traffic. That detail drives the diagnosis. You must prove whether the ABS/ESC module dropped off the network, lost power/ground, had a connector issue, or whether the CAN bus had a physical layer problem.

Theory of Operation

On Hyundai vehicles, the ABS/ESC module shares wheel speed, yaw/accel, brake requests, and stability status over the CAN network. Other modules use that data to coordinate braking, engine torque reduction, and driver warnings. The gateway and cluster also rely on those messages to decide which warning lamps to command.

C1625 sets when the expecting module stops receiving ABS/ESC messages for a calibrated time window. The root cause usually falls into one of three buckets. The ABS/ESC module lost power or ground. The CAN wiring or connectors developed high resistance, an open, or a short. Less often, a network participant or gateway disrupted bus traffic and caused timeouts without a hard “no communication” condition.

Symptoms

C1625 commonly shows up as a communication-related warning set with chassis control messages missing.

• Scan tool behavior ABS/ESC module intermittently missing from the ECU list, or data PIDs drop out during a session
• Warning lights ABS lamp, ESC/traction lamp, and sometimes brake warning lamp illuminated
• Stability control ESC/traction functions disabled or limited, especially during acceleration on low grip
• ABS operation ABS may disable or go to a fail-safe mode depending on what data is missing
• Message center “ESC OFF” or stability system warning message displayed
• Intermittent faults Symptoms appear after bumps, moisture, or under-hood heat soak
• Multiple DTCs Other modules store U- or C-codes for missing ABS/ESC data at the same time

Common Causes

• ABS/ESC module momentary reset: Low system voltage or an internal reset drops the module off the CAN network long enough to trigger a timeout.
• High resistance on ABS/ESC power or ground: Corrosion or a loose fastener causes voltage drop under load and interrupts CAN communication.
• Open or high resistance in CAN wiring: A partially broken conductor or poor splice increases network resistance and prevents clean message exchange.
• Short to power/ground on CAN circuits: Chafed insulation can pull the CAN lines out of range and stop valid data frames.
• Connector pin fit or terminal fretting at ABS/ESC: Light contact loss at the module connector creates intermittent timeouts, often over bumps.
• Water intrusion at harness/connector junctions: Moisture wicks into connectors and raises resistance, especially near the engine bay and wheelhouse areas.
• Network disruption from another controller: A different module with a wiring fault can load the CAN bus and make ABS/ESC messages disappear.
• Aftermarket device interference: Non-OEM accessories tied into power, ground, or CAN can introduce noise or abnormal bus loading.
• ABS/ESC module fault (verify last): An internal transceiver or logic fault can stop the module from transmitting even with good power and wiring.

Diagnosis Steps

You need a scan tool that can run a Hyundai network scan, read chassis DTCs, and view ABS/ESC data PIDs. Use a DVOM with min/max capture for resets. A CAN-capable scope helps on intermittent faults. Have wiring diagrams and connector views for the Kona platform before you open harnesses.

1. Confirm DTC C1625 and record freeze frame data. Focus on ignition state, vehicle speed, battery voltage, and any related CAN, ABS, or ESC codes. Note which module stored the code, if your scan tool reports it. Freeze frame shows conditions when the timeout set.
2. Run a full network scan before clearing anything. Verify the scan tool can communicate with the ABS/ESC module. If the ABS/ESC module does not appear, treat the concern as an active communication loss. If it appears, check for other modules reporting “no message” or bus faults that point to the real source.
3. Check power distribution first. Inspect and test the ABS/ESC-related fuses and main power feeds with the circuit loaded. Do not rely on visual checks alone. A fuse can pass continuity and still drop voltage under load.
4. Verify ABS/ESC module power and ground with voltage-drop testing under load. Backprobe at the ABS/ESC connector when possible. Command ABS/ESC functions with the scan tool, or use an appropriate load, to stress the circuit. Accept less than 0.1 V drop on grounds while the circuit operates. A high-resistance connection can look fine with no load.
5. Inspect the ABS/ESC module connector and nearby harness routing. Look for spread terminals, backed-out pins, fretting, corrosion, and moisture tracks. Wiggle-test the connector and harness while watching the scan tool connection status and CAN-related PIDs. Do not replace the module for a connector problem.
6. Inspect CAN harness sections that commonly move or chafe. Follow the harness from the ABS/ESC unit toward the main body harness. Check for rub-through, pinch points, previous repairs, and poor splices. Repair wiring faults using correct splicing methods, then re-check communication.
7. Check CAN physical layer behavior with ignition ON. Measure at an accessible point, preferably at the ABS/ESC connector, because CAN bias voltage only exists when powered. Compare readings on CAN High and CAN Low for stability while you wiggle the harness. Unstable bias or a line pulled toward power/ground supports a short or loading fault.
8. If the fault acts intermittent, use a scan tool snapshot during a drive test. Trigger the snapshot when the ABS/ESC warning lights appear or when communication drops. Snapshot captures live conditions during the event. Freeze frame captured the original set conditions, so use both.
9. Isolate network disruption if multiple modules show communication codes. Disconnect suspected aftermarket devices first. If needed, follow Hyundai service information for controlled module disconnect testing. Keep ignition OFF when connecting or disconnecting controllers. Restore the network step-by-step to identify which branch drops the bus.
10. Clear codes and perform a confirmation test. Re-run the network scan and verify no modules show “no communication” status. Road test under similar freeze frame conditions. Recheck for pending versus confirmed results. Some communication faults set quickly when hard-failed, while intermittent faults may only log pending until they repeat.

Professional tip: Treat C1625 as a “suspected trouble area” code, not a part verdict. A module can time out because it lost power for 100 milliseconds. Min/max voltage capture at the ABS/ESC feed during a wiggle test often finds the real issue faster than chasing the CAN pair first.

Possible Fixes

• Clean and secure ABS/ESC power and ground connections: Correct high-resistance joints, then verify with a loaded voltage-drop test.
• Repair CAN wiring defects: Fix opens, shorts, and damaged shielding/twists, and restore proper routing and strain relief.
• Service connector terminal issues: Address fretting, corrosion, pin fit, and moisture intrusion at the ABS/ESC and harness junction connectors.
• Correct power distribution faults: Replace failed fuses, relays, or damaged fuse box terminals only after proving voltage drop or heat damage.
• Remove or rework interfering aftermarket equipment: Re-route accessory power/grounds and eliminate any CAN taps that load the network.
• Replace and program the ABS/ESC module only after verification: Consider the module last, and confirm stable power/ground and a healthy CAN physical layer before replacement.

Can I Still Drive With C1625?

You can often drive a 2019 Hyundai Kona with C1625, but you should treat it as a safety-system communication fault. This code means the network lost messages from the ABS/ESC side long enough to time out. When that happens, Hyundai typically disables or limits ABS, ESC, and traction-related functions. Normal engine power may feel unchanged, yet braking stability can change fast on wet or loose surfaces. Drive only if the brake pedal feels normal and the red brake warning stays off. Avoid hard braking, high speeds, and steep descents. If multiple warning lamps appear, or the speedometer and other modules act erratic, stop and diagnose the CAN network before further driving.

How Serious Is This Code?

C1625 ranges from an inconvenience to a real safety concern, depending on what drops off the CAN network. If only intermittent timeouts occur, you may see brief ABS/ESC lamps with no drivability change. The risk rises when the ABS/ESC module power or ground drops out, or the CAN wiring intermittently opens or shorts. In those cases, ABS and stability control can stay offline. Wheel slip control may stop working, and the vehicle can skid more easily during emergency maneuvers. Treat any constant ABS/ESC warning as serious, even if the car “drives fine.” Confirm whether the ABS/ESC module stays online and whether other modules log communication DTCs.

Common Misdiagnoses

Technicians often replace wheel speed sensors or a steering angle sensor because the ABS/ESC lamp shows up with C1625. That wastes time because C1625 points to a CAN timeout, not a sensor signal fault. Another common miss involves clearing the code and calling it fixed after the lights go out. The timeout returns once vibration, heat, or load changes the network condition. Many also condemn the ABS/ESC module early without verifying power, ground, and CAN integrity under load. To avoid wasted parts, first confirm scan-tool communication to the ABS/ESC module, then perform voltage-drop checks on its feeds and grounds, and finally inspect CAN twisted-pair wiring and connector pin fit.

Most Likely Fix

The most frequently confirmed repair direction for Hyundai C1625 involves restoring reliable communication to the ABS/ESC module, not replacing it first. Start with the basics that commonly create timeouts: a poor module power feed, a weak ground, or a connector issue at the ABS/ESC unit or a nearby junction. After you verify stable power and ground during cranking and with electrical loads on, focus on the CAN wiring. Look for pin tension problems, corrosion, or a rubbed-through twisted pair that intermittently shorts. If the module stays offline despite correct power, ground, and a healthy network, then you can justify module-level diagnosis and possible replacement or programming steps.

Repair Costs

Repair cost depends on whether the root cause is a wheel speed sensor, wiring, connector condition, or the hydraulic control unit. Start with electrical checks before replacing brake system components.

Last updated: March 31, 2026