OBD-II trouble code
P22C2: O2 Sensor Pumping Current Trim Circuit/Open (Bank 2 Sensor 2)
Before anything is unplugged, read the same circuit on the other bank. If both rear trim circuits are open, no sensor on this car is at fault and replacing one cannot help — the problem is upstream of both, in shared wiring or at the module.
Quick facts
- System
- Powertrain
- Category
- Oxygen Sensor
- Severity
- Low severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $130 – $900
- DIY difficulty
- Advanced DIY
Browse every code in P2200–P22C5, or start from the full code library.
What does P22C2 mean?
Each wideband sensor carries its own calibration, encoded as a trimmed resistor inside its connector body, and the module has to read that value before it can turn raw pump current into a real oxygen figure. This code says the module went looking for the bank 2 rear sensor's calibration and found an open circuit instead.
The first move on this particular member of the family is not a test at all — it is a comparison. This vehicle has a second rear sensor with an identical circuit on the other bank, and a scan tool can tell you in seconds whether that one is reporting a trim fault as well. Those two answers point in completely different directions.
If bank 1's trim circuit is healthy and only bank 2 is open, the fault is somewhere in the part of the circuit that belongs to bank 2 alone: its sensor, its connector, its branch of the harness. That is a bounded search.
If both rear trim circuits are open, no sensor is the cause. Two independent parts do not fail the same way at the same moment, so the fault has to be in something they share — a common return, a splice that feeds both branches, a connector where the underbody loom joins the engine harness, or the module input itself. Buying a sensor at that point buys nothing, and it is a mistake that is easy to make because the code names a sensor position.
The second thing worth knowing about this address concerns work that has already been done. Check whether the two rear sensors on this vehicle carry the same part number — it is worth thirty seconds in a parts catalogue. Where they do, they are the one pair on the car that can be physically interchanged with nothing looking out of place. That is rarely true across the upstream and downstream positions, where the parts and the harness branch lengths differ. So a job that replaced both rear sensors — or that unplugged both and reconnected them in a hurry — can leave each sensor wearing the other's connector, which puts one sensor's calibration on the other's readings.
That mismatch does not always announce itself as this code. Sometimes it shows as a trim value that is present but wrong, and sometimes the pigtails simply will not reach, which is the lucky outcome because it forces the error into the open. Where a rear sensor has recently been fitted and the circuit now reads open, the provenance of that part is the thing to establish: a universal sensor with a generic plug has no trim resistor in it at all, and a spliced pigtail leaves the original resistor behind on the old sensor.
Where no work has been done, the causes are conventional — an open conductor in the bank 2 underbody run, a terminal corroded through in a connector that lives in road spray, or a failed resistor inside the connector body.
Common causes
- Open conductor on the bank 2 trim circuit between the rear connector and the module
- Corroded or backed-out terminal on the trim pin in the rear sensor connector
- Shared splice or common connector serving both rear sensors, when both banks report a trim fault
- A replacement rear sensor without its own calibration resistor, such as a universal part
- Original connector pigtail cut and spliced, leaving the trim resistor on the discarded sensor
- Rear sensor connectors interchanged between banks during a job that replaced both
- Failed trim resistor inside the connector body
- Module trim input failed, which is the least likely single cause
Symptoms
- Check engine light with the engine running and driving entirely normally
- Code appearing within a drive cycle or two of rear sensor work
- Catalyst monitor not completing on bank 2, so emissions readiness will not set
- No trim value readable for the bank 2 rear sensor on a capable scan tool
- A trim fault reported on both rear sensors at once, pointing at shared wiring
- An aftermarket, universal or visibly non-original connector at the bank 2 rear position
- Rear sensor live data still present but flagged as not trusted by the module
Diagnostic steps
- 1.Read all stored codes and check whether the bank 1 rear trim circuit is also reporting a fault. This single comparison decides whether the search is bounded to bank 2 or has to start at the shared wiring, and it costs nothing.
- 2.If both banks report trim faults, work the shared path first: the connector where the underbody loom meets the engine harness, any common splice, and the module connector. Do not order a sensor on this branch of the diagnosis.
- 3.If only bank 2 is affected, establish whether that sensor has ever been replaced and what was fitted. A universal part or a spliced pigtail explains the open on its own.
- 4.Inspect the bank 2 rear connector for a moulded original body versus an adapter, splice or generic plug, and check that the pigtail reaches its clip naturally rather than being stretched across from the other side.
- 5.Measure resistance across the trim pins on the sensor side of the connector and compare with the vehicle's specification. An open with a genuine sensor fitted moves the search to the connector body or the harness.
- 6.With both ends disconnected, check continuity on the trim conductor from the rear connector through to the module pin, flexing the loom at clips and at any point where it has lost support.
- 7.Inspect the connector cavity for water ingress, corrosion on the trim terminal and a terminal that has backed out of its lock.
- 8.After repair, clear all codes and drive until the bank 2 catalyst monitor completes, which is the only confirmation that the module is now working from a real calibration.
Repair cost
$130 – $900
Where the answer is shared wiring or a connector, the repair is $130 to $450 and no sensor is needed, which is exactly why the both-banks check comes first. Pigtail or connector replacement with a correct lead is $150 to $450. Harness repair on the bank 2 underbody run is $200 to $600. Fitting the correct original-specification rear wideband sensor is $280 to $750 installed, and a part that has already been threaded into the exhaust is generally not returnable. Diagnostic time is $100 to $220. Module work is rare and runs $500 to $900 with programming.
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 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.