OBD-II trouble code
P0058: HO2S Heater Control Circuit High (Bank 2, Sensor 2)
The heater in the post-catalyst sensor on bank 2 is faulted. This sensor does not control fuelling at all — the real consequence is that the catalyst monitor never runs, so the car fails an emissions test on readiness rather than on tailpipe numbers.
Quick facts
- System
- Powertrain
- Category
- Oxygen Sensor
- Severity
- Low severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $0 – $350
- DIY difficulty
- Intermediate DIY
What does P0058 mean?
P0058 concerns the heater in the sensor mounted after the catalytic converter on bank 2, and the single most important thing about it is what that sensor is not for. It does not trim fuel. It has no role in how much fuel the injectors deliver, and the engine's fuelling strategy will carry on completely unaffected by it.
Its job is to grade the catalytic converter. The module compares what the pre-catalyst sensor sees going in against what this sensor sees coming out. A healthy converter stores and releases oxygen, which smooths the signal, so the downstream trace should be lazy and relatively flat while the upstream one swings. When the downstream signal starts mirroring the upstream one, the converter has stopped doing its job. That comparison is the entire purpose of this sensor's existence.
Which leads to the practical consequence, and it is a specific one that catches people out. The catalyst efficiency monitor cannot run without a working downstream sensor, so with this code stored the monitor never completes and never sets to ready. At an emissions test that produces a distinctive result: the tailpipe measurements may be perfectly clean, and the car still fails — not on what it emitted, but because the on-board system has not finished checking itself. People are frequently told their car passed the sniffer and failed the test, and this is one of the reasons why. Clearing the code and driving straight to the test station does not help either, since clearing resets the monitors and they need a full drive cycle to complete.
The heater is there for a reason worth understanding. Gas that has already passed through a converter is cooler than gas in the manifold, and at idle, in traffic, or on a cold day it can be too cool to keep the sensing element in its operating range on exhaust heat alone. Without the heater the sensor simply drops out of range during exactly the low-load conditions the monitor wants to run in.
Where this sensor lives shapes both its failure population and its repair cost, and both differ from the pre-catalyst position. It is underneath the vehicle, behind the converter, with its harness clipped along the floorpan or against a heat shield. Its enemies are therefore road salt, standing water, stone strike, and the specific nuisance of a heat shield that has rusted loose and is now resting against the sensor lead. It does not live in manifold heat, so it seizes less stubbornly, and on most vehicles it can be reached from below on stands without removing anything. That combination makes it the cheapest oxygen sensor on the car to change — and unlike the upstream position, it is usually a simple narrowband sensor rather than a wideband air/fuel device, at a fraction of the part price.
One reading is worth taking before any part is ordered. Upstream and downstream heaters on the same bank commonly share a fused feed or a relay. If this code arrived alongside its pre-catalyst counterpart, the honest first hypothesis is one supply, not two failed sensors. Two sensors quoted where a single fuse is at fault is a specific and avoidable overcharge on this position.
Common causes
- Corroded connector under the vehicle after exposure to road salt and standing water
- Heater circuit wiring damaged by a heat shield that has rusted loose and is resting against the lead
- Stone strike or road debris damage to the harness along the floorpan
- Open or high-resistance ground on the heater circuit
- Control wire shorted to a voltage source where insulation has failed against a chassis-routed circuit
- Blown fuse or failed relay in the supply shared with the other heater circuits on that bank
- Failed heater element inside the downstream sensor
- Harness disturbed or clipped incorrectly after exhaust or converter work
- Failed heater driver inside the engine control module
Symptoms
- Check engine light on with no change whatsoever in how the vehicle drives
- Emissions test failure recorded as not ready or incomplete rather than as excessive emissions
- Catalyst monitor showing as not complete on a scan tool after many miles of driving
- Downstream sensor voltage flatlining or reading implausibly during idle and light load
- No change in fuel economy, which is expected and is not reassurance
- A companion upstream heater code on the same bank, pointing at a shared supply
- Fault more likely to appear during cold weather or after driving on salted roads
- Code returning shortly after exhaust or converter work
Diagnostic steps
- 1.Check whether the pre-catalyst heater code on the same bank is also stored. Both together points at one shared fuse, relay or ground rather than two failed sensors.
- 2.Confirm the fuse and relay supplying the heater circuits before testing anything on the sensor itself.
- 3.Put the vehicle on stands and inspect the sensor connector directly. Corrosion from road salt is the leading cause at this position and is visible.
- 4.Look for a heat shield that has rusted loose and is contacting or has chafed the sensor lead, which is a fault specific to under-vehicle sensors.
- 5.Inspect the harness along the floorpan for stone strike damage and for clips that were not replaced after exhaust work.
- 6.Measure the heater ground path back to its termination point, since an open ground drives the reading high.
- 7.With the sensor unplugged and the key on, check the control and ground circuits for voltage that should not be present.
- 8.Measure heater element resistance across the two heater pins and compare against the manufacturer's specification.
- 9.Confirm that the replacement part is the correct narrowband sensor for the application rather than assuming it matches the upstream one.
- 10.After repair, drive a full monitor completion cycle and verify the catalyst monitor sets to ready before booking an emissions test.
Repair cost
$0 – $350
A blown fuse or a cleaned and reseated connector is $0 to $50 and is a genuine outcome, particularly when an upstream heater code arrived at the same time. A wiring or connector repair under the vehicle is $60 to $220. The sensor itself is where this position is markedly cheaper than the pre-catalyst one: a downstream narrowband sensor is typically $30 to $130 for the part, and $120 to $300 fitted, because it is normally reachable from below without removing anything. A quote that prices this sensor the same as the upstream wideband is worth questioning. Budget nothing for diagnosis beyond an hour — this is one of the more tractable codes in the catalogue.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with oxygen sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.