Hybspec

U0270

Wysoki

Lost Communication with Control Module in CAN Network – Reverse input circuit error. The code indicates a break or disturbance in data transmission between vehicle control units.

OBD-II (EN): Lost Communication with Rear Input Circuit Control Module

Code U0270 signals a communication problem in the vehicle's CAN network – the system that connects all control modules. The cause may be a damaged wiring harness, a corroded connector, or a faulty electronic module. Due to the complexity of CAN network diagnostics, we recommend a visit to a workshop with professional diagnostic equipment.

Symptoms

MIL or service light illuminates on the dashboard. Problems may occur with systems dependent on CAN communication (e.g., ABS, ESP, HVAC, transmission). The vehicle may enter limp mode limiting performance. Intermittent shutdowns or restarts of modules. No response to commands from the control panel or key fob.

Possible causes

• Damage or break in the CAN bus wiring harness (CAN High / CAN Low) • Corrosion or loose connectors on control module plugs • Faulty control module (ECU/BCM/TCM) causing disturbances on the bus • Short circuit of one CAN line to ground or power • Damaged CAN bus terminating resistor (typically 120 Ω at each end) • Electromagnetic interference from a faulty alternator or ignition coils

Affected systems

Magistrala CAN (Controller Area Network)Moduł sterowania silnikiem (ECU/ECM)Moduł sterowania skrzynią biegów (TCM)Moduł nadwozia (BCM)Układ ABS/ESPUkład zasilania i rozruchu

Related codes

U0300Wysoki

Niezgodność oprogramowania wewnętrznego modułu sterującego. Kod wskazuje na konflikt wersji oprogramowania między modułami ECU w sieci CAN pojazdu.

Komunikacja sieciowa
Sprawdź szczegóły →

Does code U0270 require professional diagnostics?

The code alone is not enough. To find the cause, you need to read live data, check freeze frame conditions, and compare with vehicle behavior. Book a diagnostic session.