P2243

Code

LAND ROVER P — Powertrain

Oxygen sensor reference voltage - open circuit. Bank 1 - sensor 1

Brand: LAND ROVER

Type: P — Powertrain

Views: UK: 13 EN: 70 RU: 49

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Page language: EN

Causes

Open or shorted wiring to the Bank 1 Sensor 1 reference or signal circuit
Poor or corroded connector at the sensor or harness
Faulty upstream oxygen sensor (Bank 1 Sensor 1)
Blown fuse or failed relay supplying sensor circuits or ECU reference
Faulty ECU (rare) or internal reference circuit failure

Symptoms

Check Engine Light (MIL) illuminated
Poor fuel economy or rich/lean running
Rough idle or hesitation
Failed emissions test or increased tailpipe emissions
Delayed or unstable closed-loop fuel control

What to check

Read freeze frame and live data for Bank 1 Sensor 1 and fuel trims
Verify presence of related trouble codes (heater circuits, other O2 sensors)
Visually inspect sensor connector and wiring for damage, corrosion, or disconnection
Backprobe sensor connector with key ON (engine OFF) to check reference and ground presence
Inspect fuses/relays and ECU grounds related to sensor circuits

Signal parameters

Upstream narrowband O2 sensor signal (when operating): typically switches between ~0.1–0.9 V (varies by sensor type)
Sensor reference line (ECU-provided) should be present at the connector when key ON — loss indicates open circuit
Heater supply: typically battery voltage when relay/fuse active; heater current/resistance varies by sensor
Note: exact voltages and resistances vary by model year and sensor type — consult vehicle wiring diagram and service data

Diagnostic algorithm

Retrieve and record all codes and freeze-frame data. Confirm P2243 is current.
Inspect Bank 1 Sensor 1 connector and harness for corrosion, melted insulation, chafing, or open wires. Repair any visible damage.
With ignition ON (engine OFF) backprobe the sensor connector: check for the expected ECU reference voltage and sensor ground/return continuity to ECU. If reference is missing, trace wiring toward ECU looking for breaks.
Check continuity between the sensor reference pin and the ECU connector. Repair any open circuit or high resistance found.
Verify heater supply and related fuses/relays. A heater failure usually sets separate heater codes but confirm supply and grounds are good.
Wiggle test wiring and connectors while monitoring live data to detect intermittent opens.
If wiring and connectors test good, test the sensor: measure sensor internal resistance (if specified) or substitute known-good sensor to confirm operation.
If sensor replacement fixes the circuit issue, clear codes and perform a test drive to confirm no return of the code. If wiring to ECU is suspect, inspect ECU connector and grounds; replace or repair as needed.
Safety note: avoid shorting pins when backprobing; disconnect battery when performing wiring repairs.

Likely causes

Broken/disconnected reference wire at sensor connector
Corroded or bent pins in sensor connector causing open circuit
Damaged wiring due to heat/chafe near exhaust manifold
Failed oxygen sensor (internal wiring open)
Grounding problem or loss of sensor reference from ECU

Fault status

⚠️ Status

Open circuit or missing reference voltage detected on Bank 1 Sensor 1 oxygen sensor. The ECU cannot read a valid upstream O2 sensor reference, which may cause the ECU to default fuel strategy and trigger MIL.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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P2243 — Oxygen sensor reference voltage - open circuit. Bank 1 - sensor 1