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P1131

HO2S Circuit Low Variance Bank 1 Sensor 2.

  • Chrysler
  • Powertrain
  • Manufacturer code
  • Low severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
1
AreaFuel and air metering
31
FaultThe specific fault in that area

What it means

On Chrysler, P1131 means the engine control unit saw too little voltage variation from the Bank 1 Sensor 2 heated oxygen sensor, the one after the catalytic converter. The signal stayed low, flat or stuck rather than moving as expected during monitoring. It can point to the sensor, its wiring, or an exhaust or air leak that affects the reading, and the exact test conditions vary by model and engine.

Symptoms

  • Malfunction indicator lamp on
  • Usually no obvious change in driving
  • Possible slight rise in fuel consumption
  • Emissions or MOT test failure
  • Occasional rough running if a fuel or air fault is behind it

Possible causes

  • Worn, contaminated or failed rear (post-catalyst) oxygen sensor on Bank 1likely
  • Damaged, chafed or corroded sensor wiring or connector, including signal or ground faultslikely
  • Exhaust leak near the sensor or upstream of it letting in air and skewing the readingpossible
  • Sensor heater circuit fault, fuse or power supply problempossible
  • Engine running lean or rich from a fuel, vacuum leak or air metering faultpossible
  • Degraded catalytic converter giving an abnormal downstream signalrare
  • Faulty engine control unitrare

How to diagnose

  1. Read all stored and pending codes and note freeze frame data such as engine temperature, load and fuel trims
  2. Check for related codes covering the upstream sensor, heater circuits, misfires or fuel trim faults and deal with those first
  3. Visually inspect the Bank 1 Sensor 2 wiring and connector for heat damage, chafing, water ingress and corrosion
  4. Inspect the exhaust from manifold to sensor for leaks, cracks or loose joints
  5. Check short and long term fuel trims at idle and at 2500 rpm to see if the engine is running lean or rich
  6. Watch the live sensor voltage on a warm engine and see whether it moves when the mixture is changed, for example with a brief throttle snap
  7. Check the sensor heater circuit for supply, ground and resistance against the manufacturer specification for your model
  8. Test the wiring for continuity and shorts to ground or voltage, and only then consider the sensor itself or the catalytic converter condition

How to fix

  • Repair or replace damaged wiring, terminals or the connector
  • Replace the Bank 1 Sensor 2 oxygen sensor if it is slow, stuck or fails its heater or signal tests
  • Repair any exhaust leak and renew gaskets or faulty joints
  • Fix the underlying fuel, vacuum leak or air metering fault causing abnormal mixture
  • Replace a failed catalytic converter only if testing confirms it is the cause
  • Clear the code after repair and road test to confirm it does not return

Can I keep driving?

Low severity

The car can normally be driven while you book it in, as this fault rarely affects driveability. Do not leave it long, since an underlying fuel or exhaust fault could harm the catalytic converter and the car may fail an emissions test.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

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