C1123 – Yaw Rate Sensor (YRS) in YRS or G sensor circuit assembly fault (Suzuki)

Suzuki-specific code — factory diagnostic data

C1123 means the Suzuki Swift has a fault stored in the ABS/ESP system related to the yaw rate sensor inside the YRS or G sensor circuit assembly. You will usually notice stability control warnings and reduced traction assistance first. The car may still drive, but it will not correct a skid as well. According to Suzuki factory diagnostic data, this code indicates a fault in the Yaw Rate Sensor (YRS) within the YRS or G sensor circuit assembly. Treat it as a “suspected circuit area” code. Do not assume the sensor itself failed until you prove power, ground, and signal integrity.

C1123 Quick Answer

C1123 on a Suzuki Swift points to a fault in the yaw rate sensor within the YRS/G sensor circuit assembly. Verify the sensor assembly power, ground, and signal circuits at the ABS/ESP module before replacing parts.

What Does C1123 Mean?

The ABS/ESP module detects a problem with the yaw rate sensor that lives in the YRS or G sensor circuit assembly. In practice, the module can no longer trust vehicle rotation feedback. As a result, ABS may still work, but ESP stability corrections often reduce or shut off.

The official definition states: “Yaw Rate Sensor (YRS) in YRS or G sensor circuit assembly fault.” That definition tells you the suspected trouble area only. The ABS/ESP module sets C1123 after it checks the yaw sensor’s electrical circuit and signal plausibility. Those checks may include supply voltage presence, ground integrity, and whether the yaw signal behaves as expected. This matters because a wiring, connector, or power/ground problem can mimic a “bad sensor” every time.

Theory of Operation

Under normal conditions, the Suzuki Swift ABS/ESP module uses yaw rate data to understand how fast the car rotates around its vertical axis. It combines that data with wheel speed and steering angle. The module then applies brake pressure to individual wheels to stabilize the car.

C1123 sets when the ABS/ESP module cannot rely on the yaw rate signal from the YRS/G sensor circuit assembly. An open, short, poor ground, or unstable supply can corrupt the signal. The module may also flag the circuit when the yaw signal becomes implausible compared to other inputs. That failure stops accurate stability calculations, so the system limits ESP intervention.

Symptoms

Drivers and technicians typically notice these symptoms when C1123 sets:

• Warning lights: ESP/traction control light on, often with an ABS warning
• Stability disabled: Traction control or ESP turns off or shows “OFF” status
• Reduced intervention: Less corrective braking during a skid or abrupt lane change
• Stored chassis code: C1123 present in the ABS/ESP module memory
• Intermittent behavior: Warning lights come and go over bumps or during turns
• Calibration related: System requests or fails yaw/zero-point calibration after service
• Drive feel: More wheel spin on slick surfaces with traction control disabled

Common Causes

• Open circuit in YRS/G sensor power feed: A broken feed wire or failed supply path prevents the assembly from powering up, so the ABS/ESP module loses the yaw signal.
• High-resistance ground in the YRS/G sensor assembly circuit: Corrosion or a loose ground raises resistance and drags sensor operating voltage down under load.
• Signal circuit open or short between the YRS/G assembly and ABS/ESP: A rubbed-through harness can open the line or short it to ground or battery, which matches common SAE J2012-DA FTB circuit subtypes.
• Connector fretting, water intrusion, or terminal spread at the sensor assembly: Small terminal contact problems create intermittent dropouts and erratic data that the module flags as a circuit assembly fault.
• Incorrect sensor assembly power/ground shared-circuit issue: Another load on a shared splice can backfeed or pull voltage down and corrupt the YRS/G assembly circuit.
• Aftermarket electrical accessory interference: Poorly grounded add-ons can inject noise or create voltage dips that disrupt the yaw/lateral G sensor circuit signals.
• Improper installation or damage to the YRS/G sensor circuit assembly: A shifted mount, pinched connector, or stressed pigtail can break internal connections and mimic a wiring fault.
• ABS/ESP module pin fit or internal driver fault (less common): A damaged terminal at the module or an internal fault can prevent proper sensor supply or signal processing after all external checks pass.

Diagnosis Steps

Use a scan tool that can access Suzuki ABS/ESP data and run a full network scan. Have a digital multimeter, back-probe pins, and a wiring diagram for the Swift. Include a test light or fused jumper for load testing. Plan time for voltage-drop checks under load, not just continuity.

1. Confirm C1123 in the ABS/ESP module and record DTC status. Save freeze frame data, especially battery voltage and ignition state when the code set. Note any companion ABS/ESP codes related to power supply, sensor supply, or stability control. Freeze frame shows conditions at the set event. A scan tool snapshot helps catch an intermittent dropout during a road test.
2. Perform a fast visual inspection before meter work. Check battery terminals, body grounds, and obvious harness damage. Focus on the yaw rate sensor (YRS) / G sensor circuit assembly area and its harness routing. Look for moisture, carpet water intrusion, or signs of prior interior work that could stress wiring.
3. Check fuses and power distribution that feed ABS/ESP and the sensor supply circuits. Verify the fuse fits tight and shows no heat damage at the blades. Do not rely on a visual fuse check alone. Confirm power on both sides of each related fuse with the circuit powered.
4. Verify ABS/ESP module power and grounds with voltage-drop testing under load. Command an ABS/ESP function that wakes the module, or use key-on conditions per Suzuki service information. Measure voltage drop from battery positive to the module B+ feed, then from module ground to battery negative. Keep ground drop under 0.1V while the circuit operates. High resistance can pass continuity yet fail under load.
5. Inspect the YRS/G sensor assembly connector and ABS/ESP connector for terminal issues. Look for backed-out pins, terminal spread, green corrosion, and water tracks. Gently tug each wire at the rear of the connector to find broken strands. Correct any pin-fit problem before deeper testing.
6. Use the scan tool to view YRS and G sensor related live data PIDs. Watch for a flat-lined reading, implausible jumps, or “not available” status. With the vehicle safely stationary, check whether yaw rate and lateral G show stable near-zero values. If data drops out when you wiggle the harness, you have an intermittent circuit fault.
7. Identify the FTB suffix in your scan report if available (for example, -11 short to ground, -12 short to battery, -13 open circuit, -1C intermittent/erratic, -31 no signal). Use that subtype to choose your next test. An “open/no signal” pattern pushes you toward continuity and load tests. A “short” pattern pushes you toward isolation and short-to-power/ground checks.
8. Test the YRS/G sensor assembly power and ground at the sensor connector with the circuit powered. Back-probe the connector and verify the feed stays stable while you load the circuit. Use a test light or a known load to stress the circuit, then repeat voltage-drop checks across the feed and ground paths. If voltage sags under load, repair the high-resistance point instead of replacing the sensor.
9. Check the signal circuits between the YRS/G sensor assembly and the ABS/ESP module. With connectors disconnected as required by service information, test for shorts to ground and shorts to battery on each relevant line. Then perform an end-to-end continuity check. Follow up with a loaded test where possible, since a marginal wire can pass continuity at low current.
10. If the fault acts intermittent, perform a controlled wiggle test and vibration test while monitoring live data and DTC status. Move the harness near connectors, bends, and any clip points. Use a scan tool snapshot to capture the moment the yaw/G data drops or spikes. Compare snapshot timing to when the code flips from pending to stored.
11. Clear DTCs and perform a verification drive. Recheck for pending versus confirmed C1123 after the drive cycle. Remember that some faults may set as pending first, then confirm on a second trip. A hard circuit fault monitored continuously often returns quickly at key-on. Confirm stability control and ABS/ESP operation and ensure no new related codes appear.

Professional tip: Treat C1123 as a “suspected circuit area” message, not a parts verdict. On Suzuki systems, a weak ground or connector fretting can produce a clean-looking voltage reading with no load. Always repeat checks with the circuit operating and use voltage-drop to find hidden resistance.

Possible Fixes

• Repair open/short in the YRS/G sensor assembly harness: Restore proper continuity and insulation where the harness rubs, pinches, or breaks.
• Clean, tighten, and re-pin affected connectors: Remove corrosion, correct terminal tension, and repair backed-out or spread terminals at the sensor assembly or ABS/ESP module.
• Restore power/ground integrity: Repair high-resistance grounds, damaged splices, or poor fuse/relay contacts found during voltage-drop testing.
• Correct water intrusion source and recheck wiring: Fix leaks and dry the area before final verification, since moisture often triggers recurring circuit faults.
• Replace the YRS/G sensor circuit assembly only after circuit proof: Replace the assembly when power, ground, and signal circuits test good under load and live data still fails plausibility checks.
• Address ABS/ESP module connector or module fault after isolation: Repair pin-fit issues first, then consider module replacement only when external circuits and the sensor assembly test good.

Can I Still Drive With C1123?

You can usually drive a Suzuki Swift with C1123, but you should treat it as a stability-control fault first. The ABS/ESP module sets this code when it cannot trust the yaw rate sensor inside the YRS or G sensor circuit assembly. That sensor helps the module judge vehicle rotation. When the signal drops out or goes implausible, the module may reduce or disable ESP functions. Braking still works, but the vehicle may lose yaw-correction help during skids or emergency maneuvers. Drive conservatively, avoid aggressive turns, and increase following distance. If the ABS or ESP warning stays on, plan diagnostics soon. If braking feel changes or multiple chassis codes appear, stop and inspect.

How Serious Is This Code?

C1123 ranges from an inconvenience to a real safety concern, depending on when it sets and what else disables. If it sets once and stores as history, you may only lose ESP for that key cycle. When it sets as current, the ABS/ESP module often turns off or limits stability control because it cannot calculate yaw correctly. That matters most on wet roads, gravel, or evasive maneuvers. This code does not confirm a bad sensor. Per SAE J2012-DA Section 6.1, the DTC message names a suspected trouble area only. Treat the FTB suffix as a strong hint. For example, -11 points toward short to ground, -12 short to battery, -13 open circuit, -1C intermittent, and -31 no signal. Use that subtype to prioritize circuit checks.

Common Misdiagnoses

Technicians often replace the YRS or G sensor circuit assembly too early. They skip basic power, ground, and connector testing at the sensor and ABS/ESP module. Another common mistake involves ignoring the FTB suffix. A -13 “open circuit” subtype should push you toward harness damage, backed-out terminals, or poor pin fit before you blame the sensor. Intermittent (-1C) faults also trick people into swapping parts. Movement-related harness faults can mimic a failed sensor. Shops also overlook low system voltage and ground integrity. A weak battery or a high-resistance chassis ground can corrupt sensor signals and trigger “no signal” style subtypes. Confirm the fault with scan tool data and loaded voltage-drop tests before spending money.

Most Likely Fix

The most frequently confirmed repair direction for C1123 on a Suzuki Swift involves correcting the circuit fault in the YRS or G sensor circuit assembly wiring. Start with connector inspection and terminal tension checks. Then verify sensor power and ground under load with voltage-drop testing. If the FTB suffix indicates an open, short to ground, or short to battery, isolate the harness section with continuity and short-to-power/ground checks. The next common direction involves restoring a clean, plausible yaw rate signal after securing the sensor connector and repairing pin fit or corrosion. Only after you prove correct power, ground, and signal integrity should you consider the sensor assembly as the root cause.

Repair Costs

Repair cost depends on whether the confirmed root cause is a sensor, wiring, connector issue, or control module problem. Verify the fault electrically before replacing parts.

Last updated: April 10, 2026