Faulty temperature sensor integrated into the heated catalyst heater power switch.; Damaged or corroded wiring harness or connector at the heated catalyst or ECM.; Open or short circuit in the sensor signal or ground circuit.; Failed heated catalyst heater power switch relay or control module.; Internal ECM fault affecting the sensor input circuit (rare).

DTC codes / BMW codes / P1457

P1457 · BMWHeated Catalyst Heater Power Switch Temperature Sensor Electrical Bank 1

P1457 on BMW vehicles indicates that the engine control module (ECM) has detected an electrical fault in the temperature sensor circuit of the heated catalyst heater power switch for bank 1. The ECM monitors the sensor's signal to ensure it stays within an expected voltage range, and this code sets when the signal is out of range or the circuit is open or shorted.

SystemPowertrain

Code typeBMW specific

SeverityMedium

Fix difficultyIntermediate

AreaAuxiliary emission controls

Symptoms you may notice

Illumination of the check engine light (CEL) on the dashboard.
Often no other symptoms besides the warning light.
Possible slight decrease in fuel economy if the heated catalyst does not activate properly.
In rare cases, a faint sulfur or rotten egg smell from the exhaust when the catalyst is cold.
Intermittent code setting during cold starts or damp conditions if the fault is a poor connection.

Common causes, most likely first

Faulty temperature sensor integrated into the heated catalyst heater power switch.
Damaged or corroded wiring harness or connector at the heated catalyst or ECM.
Open or short circuit in the sensor signal or ground circuit.
Failed heated catalyst heater power switch relay or control module.
Internal ECM fault affecting the sensor input circuit (rare).

How to diagnose and fix it

Use a BMW-specific scan tool to read live data from the heated catalyst temperature sensor and compare to ambient temperature after a cold soak.
Visually inspect the sensor connector and wiring for corrosion, chafing, or loose pins; repair as needed.
Measure resistance of the temperature sensor with a multimeter and compare to BMW specifications; replace sensor if out of range.
Check for continuity and short-to-ground or short-to-power on the signal and ground wires between the sensor and ECM; repair harness if faulty.
Test the heated catalyst heater power switch relay and its control circuit; replace relay if defective.
If all external circuits and components test good, suspect the ECM and perform further diagnostics before replacement.

Don't overlook the heater power switch

The temperature sensor is often integrated into the heater power switch assembly, so a sensor fault may require replacing the entire switch rather than just the sensor.
A weak battery or charging system issue can cause intermittent sensor codes on BMW models, so always verify battery voltage and charging system operation first.
The heated catalyst system only activates during cold starts, so the fault may not appear during warm engine diagnostics; a cold soak test is essential.
Corrosion at the connector is a common cause on older BMWs, especially in regions with road salt, and can mimic a failed sensor.
This code does not always mean the catalytic converter itself is failing; the fault is strictly in the sensor circuit, so avoid replacing the converter without proper diagnosis.

Can I keep driving with P1457?

You can generally continue driving with this code, but the heated catalyst may not function, leading to increased emissions during cold starts. Avoid prolonged idling from cold and schedule diagnosis soon to prevent potential catalytic converter damage.

Tools that help

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Guidance is general and written for BMW vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.