P04F7: Catalyst Heater Circuit High Bank 2

What it means

Same as P04F6 on bank 2. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The bank 2 catalyst heater circuit powers or controls the heater for the catalytic converter on bank 2. The control module detects voltage higher than expected for the commanded operation; an open circuit or a control wire shorted to supply can cause this high-circuit fault.

Common causes

Most likely first.

1. Control line shorted to supply
2. Connector pins corroded - high contact resistance
3. Supply wire pinched against B+ source

Symptoms

• Check engine light on
• Possible increase in cold-start emissions

How to diagnose it

1. Save freeze-frame data and check the bank 2 heater command and circuit status at the time the high-circuit fault occurred.
2. Power down the system as directed by the manufacturer, then inspect bank 2 heater wiring and connectors for an open, corrosion, moisture, pin push-back, or contact with a power source.
3. Check the bank 2 heater control circuit for a short to supply, including any pinched wire near a power source, using the manufacturer's isolation procedure.
4. Inspect connector seating and pin contact; measure circuit continuity and voltage under the specified test conditions against the manufacturer's specification.
5. If the wiring and connections pass, test the bank 2 heater element and control circuit for an open.

Common fixes

• Reseat a pushed-back or loose bank 2 heater connector pin.
• Repair an open in the bank 2 heater wiring or element circuit.
• Repair a bank 2 heater control wire pinched against a supply source.
• Replace the bank 2 heater if it fails the manufacturer's open-circuit test.

Can I keep driving?

The fault can reduce cold-start emissions performance, though normal driving may remain possible if the engine runs normally. Arrange diagnosis soon, and use extra caution around high-voltage components on hybrid vehicles.