P0056

Heated Oxygen Sensor (HO2S) Heater Control Circuit (Bank 2 Sensor 2)

Car Fault Codes Emissions & exhaust

Can you still drive? Yes, normally

Who can fix it? DIY with some experience

Typical repair time 30 minutes – 1.5 hours

Typical cost SAR 100 to 900

What it means

An oxygen sensor has an electric heater that brings it to working temperature quickly. The engine computer has detected a fault in the heater circuit of the Bank 2 Sensor 2 oxygen sensor (downstream of the catalytic converter), most often an open heater, wiring or power feed. This sensor monitors the catalytic converter, so driving is usually unaffected, but the converter self-test cannot complete. This code applies to engines with two cylinder banks, such as V engines.

Symptoms4

Check engine light on.
Usually no noticeable driving symptoms.
Catalyst readiness monitor does not complete.
Failed emissions inspection because of the warning light.

Possible causes5

Heater element inside the sensor has failed open (the most common cause).
Blown heater fuse or lost power feed.
Melted or broken wiring near the exhaust.
Corroded or loose connector.
Fault in the control circuit inside the ECU (rare).

How to diagnose5

Check the oxygen sensor heater fuse and note whether other heater codes are stored.
Unplug the sensor, measure heater resistance at its terminals and compare it with the manufacturer specification; an open reading means a failed heater.
With the ignition on, confirm battery voltage reaches the heater feed terminal in the connector.
Check continuity of the control wire back to the ECU, and inspect the wiring near the exhaust.
Clear the code, warm up the engine and see whether it returns.

How to fix5

Replace the fuse if it has blown, after making sure no short is causing it.
Clean the connector, repair any broken or melted wire, and route the wiring away from the exhaust.
Replace the oxygen sensor if heater resistance is out of specification.
Have the ECU checked if the wiring and sensor are fine (rare).
Clear the codes, drive until the sensor tests complete and confirm the code does not return.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low when a fuse or wire is to blame, and rises when the oxygen sensor must be replaced; its price depends on the sensor type and the vehicle.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

Does this code affect how the car drives?

Usually not, because the downstream sensor mainly monitors the catalytic converter rather than controlling the mixture. It does stop the converter test from completing and causes an emissions test failure.

Can the heater be repaired without replacing the sensor?

No. The heater is built into the sensor, so a failed heater means replacing the whole sensor. Check the fuse and wiring first, though, because they are cheaper to fix.

Why did heater codes for several sensors appear together?

That points to a shared cause such as the heater fuse or a common power feed, rather than every sensor failing at the same time.

This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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