What is the difference between this and P2240?

P2240 says the module cannot drive current through the circuit at all. P2241 says it can, but the amount is below what it expects. Practically, an open points at a break, a disconnected plug or a dead cell, while a low reading points at something adding resistance in series or bleeding current away to ground. That is why bad splices, corroded terminals and chafed insulation dominate this code and not the other one.

I fitted a universal oxygen sensor and now I have this code. Is that the cause?

It is the first thing to suspect. A universal sensor requires you to cut the original wiring and create several new joints in a circuit that works in milliamps and whose calibration assumes an unbroken path. Even good crimps add resistance, and under-car joints take on moisture. Fitting the correct connectorised sensor for the vehicle is usually the cheapest way out, because chasing the fault around a spliced harness costs more in labour than the part saved.

The code only appears when the car is warmed up. Why?

Because contact resistance rises with temperature and because heat expands connector terminals and joints out of proper contact. A marginal connection can carry enough current at ambient temperature to satisfy the module and fall below the threshold once the engine bay is hot. It means testing on a cold engine will pass. Get it hot, then do the voltage drop test under load.

Should I just replace the sensor?

Not before checking the wiring, because on a low reading the odds favour the circuit. Look for previous splices, inspect the lead where it touches metal, and do a hot voltage drop test. If all of that is clean and the bank 1 sensor behaves normally under the same conditions, the sensor becomes the reasonable next step — but replacing it first and finding the code returns is a common and avoidable expense.

OBD-II trouble code

P2241: O2 Sensor Positive Current Control Circuit Low (Bank 2 Sensor 1)

Current is reaching the bank 2 wideband pump cell, but less of it than the module expects. That distinction matters: a previous repair to this circuit is one of the most common reasons it reads low.

Medium severityPowertrainOxygen SensorDrivable short-term

Quick facts

System: Powertrain
Category: Oxygen Sensor
Severity: Medium severity
Drivable: Usually safe to drive short-term
Repair cost range: $120 – $900
DIY difficulty: Advanced DIY

What does P2241 mean?

The module measures what it is achieving in the pump current circuit of the bank 2 upstream wideband sensor and finds the value sitting below the window it expects. This is a different situation from an open circuit, and it is worth being precise about why, because the two lead to different suspects.

An open circuit is a verdict of absence. A low reading is a verdict of insufficiency: the circuit is intact, current is flowing, and the module rejected the amount. Something is standing between the module and the pump cell adding resistance, or something is bleeding part of the current away to ground before it arrives. Both leave a working-looking circuit that fails the measurement, which is why this code is so often chased with a meter that keeps saying everything is fine.

The cause that deserves naming first is a previous repair. Wideband pump circuits are unusually intolerant of the ordinary techniques that work everywhere else on a car. A crimped butt connector introduces a contact resistance that is trivial for an injector and significant for a milliamp circuit. A soldered joint left unsealed under the car takes on moisture and corrodes from the inside within a season. And the specific product that causes the most trouble here is the universal splice-in oxygen sensor: it saves the price of the correct part, but it asks you to create four to six new joints in circuits that were designed as continuous conductors, and on a wideband sensor the calibration relationship between sensor and module assumes there is nothing added in between. If this vehicle has had any oxygen sensor work, find out whether the connector was replaced properly or the wires were cut and joined. That single question resolves a large share of these.

The second route to a low reading is a partial short to ground. A pump circuit that touches a grounded surface through damaged insulation does not necessarily go dead — it loses part of its current to the shorter path, and what arrives at the cell is less than commanded. On the bank 2 upstream lead this typically happens where the harness crosses a bracket, a heat shield edge or a bellhousing bolt, and the giveaway is that the fault is often position-sensitive: it appears over bumps, on hard acceleration when the engine rocks on its mounts, or on turns. If freeze frame shows the code setting at anything other than steady cruise, weight that possibility.

A third pattern worth recognising is thermal. Joints with marginal contact and connectors with corroded terminals frequently pass when cold and fail when the underbonnet temperature is up, because expansion moves the contact surfaces and because resistance climbs with temperature. A code that only appears after twenty minutes of running, or in summer and not in winter, is pointing at contact quality rather than at a broken conductor. Testing that means loading the circuit while hot, not checking it on a cold engine in the morning and declaring it healthy.

As with every wideband circuit, the pump cell is fragile and must not be jumpered, back-probed carelessly or fed voltage to see what happens. Use live data first, then the manufacturer's specified measurement points.

Common causes

Crimped or spliced joints in the pump circuit from an earlier repair, adding resistance a milliamp circuit cannot tolerate
A universal splice-in oxygen sensor fitted in place of the correct connectorised part
Unsealed solder joint that has corroded internally since the repair
Partial short to ground through chafed insulation where the bank 2 lead crosses a bracket or heat shield
Corroded or heat-aged terminals whose resistance rises with underbonnet temperature
Water intrusion into the connector producing a leakage path to ground
Internal degradation of the pump cell in an aged or contaminated sensor
Module-side driver operating below specification, which is uncommon and needs measurement to prove

Symptoms

Check engine light, often intermittent before it becomes permanent
Bank 2 mixture value present but implausible, sluggish or slow to respond
Bank 2 dropping in and out of closed loop rather than staying out of it
Fault appearing when the engine is fully hot and absent on a cold start
Fuel economy down modestly, sometimes with no drivability complaint at all
Emissions monitors that complete inconsistently between drive cycles
Fault that comes and goes with road surface or hard acceleration when a chafe is involved
Occasional rough idle when the module briefly acts on a bad measurement before rejecting it

Diagnostic steps

1.Ask whether this circuit has been repaired before, and look for butt connectors, tape wraps, heat-shrink or a universal splice-in sensor anywhere along the bank 2 lead.
2.Read freeze frame and note engine temperature, run time and load at the moment of setting. Hot-only points at contact resistance; bumps and acceleration point at a chafe.
3.Compare bank 2 against bank 1 in live data. A bank 2 value that is present but lazy or offset is consistent with a low reading rather than an open.
4.Inspect the full length of the bank 2 lead for insulation damage at every point it touches metal, paying attention to bracket edges and heat shield lips.
5.Perform a voltage drop test across the circuit under load rather than a static resistance check, and do it with the engine at operating temperature.
6.Wiggle-test the harness and connector while watching live data, then repeat once the engine bay is hot.
7.Check for a leakage path to ground by measuring from the pump circuit to a known good ground with the circuit disconnected at both ends.
8.Where a previous splice is found, repair it properly with sealed connections or replace the section of harness before condemning any component.
9.Only consider the sensor or module after the wiring has been proved good with measurements taken hot and under load.

Repair cost

$120 – $900

Diagnosis is $100 to $250, and a fair share of that time goes on getting the vehicle hot enough to reproduce the fault. Repairing a bad splice or a chafed section is $130 to $450 and is the correct outcome more often on this code than on its open-circuit sibling — a low reading is far more likely to be a joint than a break. Replacing a universal splice-in sensor with the correct connectorised part costs $150 to $600 fitted, and is money well spent rather than a second attempt at the same shortcut. A genuine sensor failure runs $200 to $700 fitted on bank 2 depending on access. Module-side faults at $600 to $1,600 are uncommon.

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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.