is rarely a sign of a dead ECU or a complex computer failure. In over 80% of cases, the problem is a simple mechanical "link" failure —a loose yellow connector, a corroded pin, or a fatigued wire under the driver’s seat.
For , B123A most commonly points to:
Check if the rear left door:
: With the ignition on and reverse gear engaged, listen closely to each sensor; a working sensor typically emits a faint "clicking" sound. Check Battery Health dtc b123a renault link
Even if the battery is new, low voltage or an incorrect battery type (e.g., using a standard lead-acid instead of an AGM for Stop/Start models) can trigger link errors. is rarely a sign of a dead ECU or a complex computer failure