Broken or corroded power supply wire between the heated catalyst control module or relay and the bank 2 heater element.; Failed heater element inside the bank 2 catalytic converter, causing an open circuit within the heater itself.; Blown fuse or faulty relay that supplies power to the heated catalyst heater circuit.; Loose, damaged, or corroded connector pins at the heater or at the control module.; Faulty heated catalyst control module or engine control module driver circuit, though this is less common.; Rodent damage or physical abrasion of the wiring harness near the exhaust system.

DTC codes / BMW codes / P1459

P1459 · BMWHeated Catalyst Heater Power Supply Open Circuit Bank 2

Q: What does code P1459 mean?

Heated Catalyst Heater Power Supply Open Circuit Bank 2. P1459 on a BMW means the engine control module has detected an open circuit in the power supply wire to the heated catalyst heater for bank 2, which is the side of the engine that does not contain cylinder 1. The heater is an electrical element that warms the catalytic converter quickly after a cold start to reduce emissions, and an open circuit means the module sees no continuity or current flow when it commands the heater on.

P1459 on a BMW means the engine control module has detected an open circuit in the power supply wire to the heated catalyst heater for bank 2, which is the side of the engine that does not contain cylinder 1. The heater is an electrical element that warms the catalytic converter quickly after a cold start to reduce emissions, and an open circuit means the module sees no continuity or current flow when it commands the heater on.

SystemPowertrain

Code typeBMW specific

SeverityMedium

Fix difficultyIntermediate

AreaAuxiliary emission controls

Symptoms you may notice

Illumination of the check engine light, often with no other symptoms noticed by the driver.
A slight delay in catalyst light-off after a cold start, which may cause a brief emissions smell from the exhaust.
Possible reduction in fuel economy if the engine management system alters cold-start strategy to compensate.
In some cases, the engine may enter a limited-operation mode with reduced power, though this is less common.
No noticeable change in driveability during normal warmed-up operation.

Common causes, most likely first

Broken or corroded power supply wire between the heated catalyst control module or relay and the bank 2 heater element.
Failed heater element inside the bank 2 catalytic converter, causing an open circuit within the heater itself.
Blown fuse or faulty relay that supplies power to the heated catalyst heater circuit.
Loose, damaged, or corroded connector pins at the heater or at the control module.
Faulty heated catalyst control module or engine control module driver circuit, though this is less common.
Rodent damage or physical abrasion of the wiring harness near the exhaust system.

How to diagnose and fix it

Connect a scan tool and verify P1459 is current, then check for any related codes in other modules that might affect the heater circuit.
Inspect the wiring harness and connectors at the bank 2 heated catalyst for visible damage, corrosion, or loose pins.
Check the fuse and relay that supply power to the heated catalyst heater circuit, replacing any failed components.
Measure resistance of the bank 2 heater element with a multimeter and compare to the manufacturer's specification to confirm an open circuit.
Perform a voltage drop test on the power supply wire from the control module to the heater while commanding the heater on with the scan tool.
If the heater element is open, replace the bank 2 catalytic converter assembly as required by BMW procedures.
Clear the fault memory and perform a drive cycle to confirm the repair and ensure the code does not return.

What BMW technicians check before replacing parts

A common mistake is replacing the catalytic converter immediately, but the open circuit is often in the wiring or connector rather than the heater element itself.
The power supply wire can chafe against the exhaust heat shield or underbody, so inspect the entire route from the control module to the heater.
On some BMW models, the heated catalyst heater is controlled by a separate module that can fail and set this code without any issue in the heater circuit.
A weak battery or charging system fault can cause the control module to disable the heater and set a false open-circuit code, so always check system voltage first.
The bank 2 designation refers to the side of the engine opposite cylinder 1, so confirm which side that is on the specific BMW engine before testing.

Can I keep driving with P1459?

You can generally continue driving with P1459 because the fault mainly affects cold-start emissions and does not cause an immediate safety risk. Avoid prolonged idling from cold and have the circuit inspected soon to prevent further emissions system damage and to ensure the vehicle passes any emissions inspection.

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.