OBD-II trouble code
P22B8: O2 Sensor Positive Current Control Circuit/Open (Bank 2 Sensor 2)
This is the first bank 2 code in the downstream wideband set, and it comes with something the upstream bank 2 codes never have: a genuinely symmetrical twin. The rear sensors on a V engine live the same life, so bank 1 is a real control for once.
Quick facts
- System
- Powertrain
- Category
- Oxygen Sensor
- Severity
- Low severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $130 – $950
- DIY difficulty
- Advanced DIY
Browse every code in P2200–P22B8, or start from the full code library.
What does P22B8 mean?
The module drives a small current through the pumping cell of the sensor behind the catalyst on bank 2 — the bank that does not contain cylinder one — and has found the supply side of that circuit open. No current is flowing, so there is nothing to measure.
Most of what is written about bank 2 faults is about asymmetry, and for the upstream sensors that is right. On a transverse V engine the front bank and the rear bank are not comparable: one sensor is reachable from above and the other is jammed against the firewall, the harness lengths differ, one lives in a hotter pocket than the other, and the labour to replace them can differ by a factor of several. Diagnosis has to allow for all of that, which means the healthy bank is only a rough guide to the sick one.
At the downstream position that asymmetry largely disappears, and it is the most useful fact on this code. Both rear sensors sit behind their own catalyst, in the underbody airflow, at a similar distance from the module, in the same road spray, at the same height above the same road surface, reaching similar temperatures because the gas has already given up most of its heat to the converter. On many vehicles they are the same part number. For once, the bank 1 sensor is a true control: same part, same run, same exposure, same weather, same drive.
Use it deliberately rather than as a sanity check. Measure the supply at the bank 1 rear connector and at the bank 2 rear connector and compare the numbers directly. Compare the continuity readings on the two supply conductors. Compare the physical condition of the two connectors side by side, because a difference you can see between two components that have led identical lives is informative in a way that an absolute judgement about one of them never is. If bank 1 is healthy and bank 2 is open, the fault is local to the bank 2 side and there is no need to hedge about environmental differences, because there are not any worth speaking of.
The one thing the two rear sensors genuinely do share on many vehicles is a connector block or a harness junction near the transmission crossmember, where the underbody loom gathers before running forward. If both rear sensors have logged faults rather than just this one, that junction is the first place to look rather than the last.
As elsewhere in this family, the fault is almost always in the harness or a connector rather than in the sensor, and a rear sensor that reports a calm, plausible value is not thereby proven healthy — with no current flowing there is nothing for the module to report but a substitution.
Common causes
- Open supply conductor in the bank 2 underbody harness run
- Corroded terminal or crimp in the bank 2 rear sensor connector
- Damage at the shared connector block or harness junction near the transmission crossmember
- Stone or debris damage to the underbody loom on the bank 2 side
- Terminal backed out of its lock at the sensor connector or the module header
- Harness cut or pinched during exhaust, catalyst or subframe work on that side
- Open pump supply element inside the sensor
- Failed module driver for the bank 2 downstream pump circuit, which is the least likely cause
Symptoms
- Check engine light with no change in power, idle quality or fuel consumption
- Bank 2 rear sensor live data static while the bank 1 rear sensor responds normally
- Bank 2 catalyst monitor not completing, so emissions readiness will not set
- Supply voltage absent at the bank 2 rear sensor connector but correct at bank 1
- Both rear sensors logging faults together, pointing at a shared junction
- Fault appearing after exhaust, catalyst or subframe work on the bank 2 side
- Visible damage or corrosion on the bank 2 underbody loom
Diagnostic steps
- 1.Measure the same thing at both rear sensors and compare, rather than judging bank 2 on its own. The two downstream sensors lead near-identical lives, so a difference between them is meaningful in a way an absolute reading is not.
- 2.Read the full code list first. Faults on both rear sensors point at the shared connector block or harness junction near the transmission crossmember; a fault on bank 2 alone points at the bank 2 leg beyond it.
- 3.Check continuity on the bank 2 supply conductor from the sensor connector through to the module pin with both ends disconnected, then run the same check on bank 1 and compare the readings.
- 4.Open both rear sensor connectors and inspect them side by side. Corrosion, a failed seal or a backed-out terminal shows up clearly against a connector that has had the same exposure and is still sound.
- 5.Inspect the bank 2 underbody run for stone damage, crush points, broken clips and sections pinched during previous work.
- 6.Locate and open any inline connector on the bank 2 leg, since a corroded crimp inside a sealed inline connector is a common finding and invisible from outside.
- 7.With the harness proven good, measure the sensor's pump supply element resistance at the sensor side of the connector against the manufacturer's specification before condemning it.
- 8.After repair, clear all codes, confirm the bank 2 rear sensor value now tracks conditions like its bank 1 counterpart, then drive until both catalyst monitors complete.
Repair cost
$130 – $950
Repairing a corroded connector or inline crimp on the bank 2 underbody run is $140 to $420 and is the most common outcome. Harness section repair or replacement is $220 to $650. Replacing the bank 2 downstream wideband sensor is $290 to $780 fitted; the rear sensors are usually far cheaper in labour than their upstream counterparts on a transverse V because neither is buried against the firewall. Module repair or replacement with programming is $500 to $950 and is rare. Diagnostic time is $100 to $250, and comparing against the bank 1 sensor keeps it at the lower end.
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DIY vs shop
This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.