P0057 Code: O2 Sensor Heater Control Circuit Low (Bank 2 Sensor 2)
The heater behind the bank 2 converter draws no current – open element or cut, torn or unplugged wiring.
At a glance
Severity: Minor
- Meaning
- O2 Sensor Heater Control Circuit Low (Bank 2 Sensor 2)
- System
- Fuel & Air Metering · Powertrain
- Safe to drive?
- Yes, short term
- Typical repair cost
- $0–$2,800
- DIY difficulty
- Easy
P0057 means the heater in the oxygen sensor behind the bank 2 catalytic converter isn't drawing current when the engine computer switches it on; the circuit looks open. Because this sensor exists only on engines with a converter per bank and sits far back under the vehicle, physical damage plays a bigger role here than with any other heater code. Converter theft leaves cut sensor wires behind, and a hurried replacement may reuse a damaged pigtail or leave the connector unplugged. On trucks and SUVs, rocks, ice, off-road use or a jack placed under the exhaust can tear the pigtail or its frame clips. The rest of the time it's the familiar story: a heater element that burned out after years of heat cycles.
Can I keep driving? Drives normally. If the code appeared after a converter theft or underbody damage, have the whole exhaust and its wiring inspected, because leaks or loose parts matter more than the heater itself.
How to read P0057
- P Powertrain
- 0 Generic (SAE)
- 0 Fuel/air & emissions (aux.)
- 57 Specific fault
Symptoms
- Check engine light on every drive shortly after start-up
- Code appeared after a catalytic converter theft, an underbody impact or an off-road trip
- Louder exhaust or rattling as well, if the underbody was damaged
- Bank 2 downstream sensor shows no activity and its catalyst monitor stays incomplete
- Cut or dangling wires visible behind the bank 2 converter
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Heater element burned open after long service
- Wires cut or connector left unplugged after converter theft or replacement
- Pigtail or frame clip torn by debris, ice, off-road use or a misplaced jack
- Blown fuse on vehicles that feed downstream heaters separately
- Corroded terminal no longer making contact in the connector
- Heater driver in the engine computer failed open
Diagnosis step by step
Look underneath first
With the vehicle safely raised, inspect the exhaust behind bank 2. After a theft or impact, cut wires and torn clips are obvious, and you'll also spot exhaust leaks or a loose converter that need fixing anyway.
Tools: Flashlight
Unplug and measure the heater
At the sensor connector, measure across the two heater wires on the sensor side. A narrowband heater typically reads about 3 to 20 ohms depending on make; OL means it's open.
Tools: Multimeter
Check feed and control at the harness
Key on: the feed pin should show battery voltage. Then, with the engine idling cold, put the meter between the feed and control pins. When the computer switches the heater on you should see close to battery voltage there; nothing at all while the feed is present points to the control wire or driver.
Tools: Multimeter
Bench-check with the new sensor
Before fighting a seized old sensor, plug the new one into the harness and let it hang free for a short test. If the heater status reads on and P0057 doesn't return, the wiring is good. The tip gets very hot, so keep it away from wiring, undercoating and your hands.
Tools: OBD-II scanner
Repair cut wiring on the harness side only
If thieves cut the wires, repair the harness side with sealed, staggered splices, but replace the sensor rather than splicing its own pigtail. Many sensors draw reference air through their cable, and a sealed splice there can upset the reading.
Tools: Pliers
Install, secure and verify
Remove the old sensor with penetrating oil and an O2 sensor socket, install the new one and fasten the pigtail in every frame clip. Clear the code and drive until the bank 2 catalyst monitor completes.
Tools: O2 sensor socket, Torque wrench, OBD-II scanner
Where the parts are
- 1Upstream O2 sensor
- 2Catalytic converter
- 3Downstream O2 sensor
- 4Diesel particulate filter
- 5Turbocharger
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Reconnect and clip the sensor connector | Yes | $0–$20 |
| Bank 2 downstream sensor, part only | Yes | $40–$150 |
| Bank 2 downstream sensor installed at a shop | No | $130–$320 |
| Harness-side splice repair after cut wires | No | $80–$220 |
| Converter replacement after theft, including sensors | No | $900–$2,800 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Field data
| Subaru | 2 | Forester, Outback |
|---|
Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.
Emissions / smog test impact
Will fail
With the check engine light on for P0057, the vehicle fails an OBD-II smog check. If the converter was stolen, the replacement must also be an emissions-legal part for your state, or it will be rejected even with no codes.
Frequently asked questions
Can I splice the cut wires on the sensor's own pigtail?
It's better not to. Many oxygen sensors breathe reference air through their cable, and a soldered, sealed joint on the sensor side can block it and distort the signal. Splice the vehicle harness side if needed and fit a new sensor with its intact pigtail.
My converter was stolen and replaced, and now I have P0057. Why?
Thieves usually cut straight through the sensor wiring. If the shop reused the old sensor, reconnected a damaged harness or left the connector hanging, the heater circuit ends up open. Ask them to check the connection and heater resistance.
Why test the new sensor before installing it?
Downstream sensors on trucks are often seized solid. A quick test with the new sensor plugged in but not installed proves whether the harness and computer are fine before you spend an hour on a stubborn old sensor.
Does P0057 mean my bank 2 converter is bad?
No. P0057 is only about the sensor's heater. The converter can be perfectly healthy; it just can't be graded until the heater works. If a converter code like P0430 also appears after the repair, that's a separate issue.