Yes, a bad battery can cause error codes. This is because the battery supplies power to the car’s electrical system as well as providing a stable voltage for the engine control unit (ECU) and other computerized components. If the battery does not have enough charge or is failing altogether, then it cannot provide adequate power for these systems and this may lead to certain fault codes being stored in the ECU memory. Commonly seen when diagnosing vehicles with low or no charge batteries are codes such as P0302 misfire on cylinder 2, P0420 catalytic converter efficiency below threshold, and P0300 random multiple misfires detected. Aside from error codes, a faulty battery could also cause problems with starting your vehicle due to lack of sufficient energy needed by starter motor and fuel pump relay to engage correctly. To prevent any issues arising from an unreliable source of power in your car, be sure to regularly check your battery health using an appropriate tester tool or take it into a qualified technician who will diagnose it accurately.