HYUNDAI · GF-000874

i20 III

Technical identity dossier for i20 III, separating market, period, platform, powertrain and research focus.

QUICK TECHNICAL ANSWERS

What concrete information can you get from this page?

Verified application example: Europe / UK · i20 III launch/update · i20 1.0 T-GDI 48V · 1.0 T-GDI · 6iMT / 7DCT depending cited variant

VERIFIED FACTModel / system fact

A 1.0 T-GDI 48 V mild-hybrid powertrain is published for i20 III.

FAULT SEPARATIONWhen a symptom appears

For start-stop/48 V warnings check the 12 V battery, DC/DC and 48 V SOC/temperature together.

FIRST MEASUREMENTBefore replacing parts

Record key-off/running voltage and DC/DC direction for both 12 V and 48 V systems; do not decide from static battery voltage alone.

Primary source: Hyundai UK – All-new i20

PRACTICAL OWNER / WORKSHOP ANSWERS

What can you actually learn about this model?

Which application is verified?: Europe / UK · i20 III launch/update · i20 1.0 T-GDI 48V · 1.0 T-GDI · 6iMT / 7DCT depending cited variant
What is the first fault-separation step?: For start-stop/48 V warnings check the 12 V battery, DC/DC and 48 V SOC/temperature together.
What should be measured before replacing parts?: Record key-off/running voltage and DC/DC direction for both 12 V and 48 V systems; do not decide from static battery voltage alone.

Primary source to verify: Hyundai UK – All-new i20

Exact oil/fluid capacities, torque, pressure or pin values are shown only when verified in an OEM source for the matching model year, engine and market.

Technical identity summary

Source variant count: 1 · Status: CURRENT

This page does not treat the same sales name as one vehicle across all years and markets. Rows below remain separated by source region and variant identity.

i20 III · Türkiye

Record	VR-001338
Period	2020- • Current sale / production
Platform / generation	BC3
Powertrain / energy / driveline	B hatch • MPI/T-GDi; MT/DCT
Research focus	verify platform/generation, powertrain/energy/driveline and market-specific application identity against manufacturer/source records before applying parts, service procedures or chronic-fault claims.

Where should diagnosis start?

Verify generation, market, powertrain and ECU identity first; the same model name can hide technically different vehicles.

Exact OEM torque, pressure, capacity, pin or calibration values are not inferred from this normalized identity record; a verified service source is required for the exact vehicle application.

TECHNICAL SOURCE LINEAGE

Recorded application matrix and evidence boundary

Record	Region	Period	Platform	Powertrain record	Evidence
VR-001338	Türkiye	2020-	BC3	B hatch • MPI/T-GDi; MT/DCT	D · source-lineage identity; not OEM service evidence

Grade-D records are not OEM service procedures; they are source-lineage research rows preserving market/generation/powertrain identity. Exact torque, pinout, pressure or fitment is not inferred from this layer.

System architecture: what does this record indicate?

On turbo-petrol architecture, load calculation, boost target/actual, lambda/fuel trim, ignition and knock control are compared in the same event window.
ICE, 12 V, HV/48 V, DC-DC, motor-generator and thermal management are separate control layers; energy flow is aligned with the fault event.
For DCT/DSG, TCU-mechatronics, K1/K2 clutches, actuator/line pressure and input/output speeds are evaluated together.
For ADAS, bracket/glass, alignment, ride height, steering/yaw references and calibration prerequisites matter as much as the sensor DTC.

Freeze-frame and live-data package

Freeze frame: first/last fault time, RPM, load, vehicle speed, system voltage, core temperatures and companion DTCs.
Live data: calculated load, MAP/boost target-actual, throttle angle, lambda/O2, STFT/LTFT, ignition advance and knock retard.
Electrified layer: SOC/SOH where available, cell delta, pack temperatures, HVIL/isolation, contactor permission, DC-DC output and 12 V voltage.
Driveline: input/output speeds, commanded/actual ratio, clutch/TCC slip, fluid temperature, actuator/solenoid command and adaptations.

Measurement sequence

1) Match vehicle/generation/market/powertrain/driveline identity to the source record; family name alone is not fitment evidence.
2) Preserve freeze frame and companion DTCs before clearing; make the first-fault condition reproducible.
3) Verify power/ground and network communication under load; do not decide from key-on static measurement alone.
4) Compare commanded air/fuel/pressure with an independent physical result; separate sensor bias from real performance loss.
5) Compare electronic command → hydraulic/actuator response → mechanical slip/ratio result at the same temperature and load.
6) After repair, recreate the same load/temperature and verify DTC state, live-data deviation and user symptom together.

Root-cause discrimination matrix

On lean/misfire/boost complaints, align fuel trim, lambda, ignition retard and boost deviation on one time base to separate air leak, fuel-delivery and ignition causes.
For READY/charging faults, separate 12 V supply from the HV permission chain first; low 12 V can mimic contactor/HVIL/isolation faults.
For battery performance, use cell delta, temperature spread and voltage deviation under load/charge instead of one SoH percentage alone.
For DCT harshness/slip, separate TCU command from clutch slip and actuator/hydraulic response; adaptation result alone does not prove mechanical wear.
For ADAS DTCs, verify mounting geometry and calibration prerequisites before sensor replacement; alignment error can mimic an electrical sensor fault.

OEM EVIDENCE DOSSIER

Verified technical facts and application boundary

A 1.0 T-GDI 48 V mild-hybrid powertrain is published for i20 III. [S1]
The 48 V application can be paired with a 6-speed iMT or 7-speed DCT. [S1] [S2]
Hyundai describes CVVD valve-control technology together with the mild-hybrid layer in this engine family. [S2]

Verified application matches

The matches below are published only within the stated market, model-year and evidence scope. Fitment is not extrapolated to uncited variants.

System architecture and component relationships

Validate 12 V main supply, 48 V battery, BSG/ISG, DC/DC and engine-ECU layers separately; low 12 V voltage can create multiple network and start-stop faults.
At the same load point log engine torque request, 48 V SOC/temperature, BSG torque and DC/DC current direction; do not reduce start-stop diagnosis to one battery-voltage reading.
Where a dual-clutch transmission is fitted, time-align engine torque reduction, selected gear, input/output speeds and clutch state.

DTC / SPN-FMI / symptom discrimination map

For start-stop/48 V warnings check the 12 V battery, DC/DC and 48 V SOC/temperature together.
For torque fluctuation compare engine torque, BSG assistance and transmission torque coordination in the same log.
For network DTC clusters rule out a common supply/ground event before replacing modules.

Measurement and diagnostic strategy

Record key-off/running voltage and DC/DC direction for both 12 V and 48 V systems; do not decide from static battery voltage alone.
Log engine/BSG/transmission on the same time base and label start-stop events with temperature and SOC.
After repair verify start-stop, BSG assistance and shifting again at comparable SOC, temperature and load.

Exact pinouts, torque values, pressure thresholds or service limits are published only when explicitly verified by the applicable OEM service source.

Evidence provenance and primary sources

Hyundai UK – All-new i20 · OEM-primary · 2026-08-17
Hyundai Europe – New i20 technology · OEM-primary · 2026-08-17

Connected technical centers

Engine Atlas · Transmission Atlas · DTC Academy · Recall

Market and generation variants

i20 III · Türkiye · 2020-

Sources & freshness

Exact technical values, prices and failure rates are not invented without verified vehicle/manufacturer evidence.

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