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P1195

O2 Sensor 1/1 Bank 1 Sensor 1 Slow During Catalyst Monitor.

  • Dodge
  • Powertrain
  • Manufacturer code
  • Low severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
1
AreaFuel and air metering
95
FaultThe specific fault in that area

What it means

On Dodge vehicles P1195 means the upstream oxygen sensor (Bank 1 Sensor 1) responded too slowly while the engine control unit was running the catalyst monitor. The control unit watches how quickly the sensor switches between rich and lean, and when the response falls outside its limit it sets the code. This points to a lazy or contaminated sensor, or something affecting its signal, rather than automatically meaning the catalytic converter has failed.

Symptoms

  • Malfunction indicator lamp on
  • Slightly higher fuel consumption
  • Rough or unstable idle in some cases
  • Hesitation or poor throttle response
  • Failed emissions test or readiness monitors not completing

Possible causes

  • Ageing, lazy or contaminated upstream oxygen sensor (Bank 1 Sensor 1)likely
  • Damaged wiring, poor connector contact or corrosion in the sensor circuitpossible
  • Exhaust leak upstream of or near the sensor letting in false airpossible
  • Sensor contamination from coolant, oil or silicone, caused by an engine fault such as a head gasket leak or oil burningpossible
  • Fuelling problem such as a leaking injector, fuel pressure fault or vacuum leak causing abnormal mixturepossible
  • Faulty engine control unit or an outdated calibration (model and engine dependent; check for manufacturer bulletins)rare

How to diagnose

  1. Read all stored and pending codes and note the freeze frame data (engine temperature, load, speed) to see the conditions when it set.
  2. Check for other fuelling, misfire or oxygen sensor codes that may point to the underlying cause.
  3. Visually inspect the sensor wiring, connector and routing for heat damage, chafing, corrosion or water ingress.
  4. Inspect the exhaust manifold, flange joints and downpipe for leaks upstream of the sensor.
  5. Check for vacuum leaks and review short and long term fuel trims at idle and at around 2,500 rpm.
  6. Watch the live upstream sensor signal on a scan tool or oscilloscope and check it switches quickly and evenly between rich and lean.
  7. Check for signs of contamination such as coolant loss, oil consumption or a white or sooty sensor tip.
  8. Check for any applicable manufacturer service bulletins or calibration updates for the specific model and engine.

How to fix

  • Replace the upstream oxygen sensor if its response is slow or it is contaminated.
  • Repair or replace damaged wiring or connectors in the sensor circuit.
  • Repair exhaust leaks upstream of the sensor, using new gaskets or sections as needed.
  • Fix the source of contamination (for example coolant or oil ingress) before fitting a new sensor.
  • Correct any fuelling or vacuum fault that is distorting the mixture.
  • Apply a manufacturer calibration update only if one is published for this known issue on the vehicle.

Can I keep driving?

Low severity

The car can normally be driven while you book a repair, as this fault rarely causes immediate harm. Do not leave it for long, because poor mixture control can raise fuel use and emissions and may eventually load the catalytic converter.

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

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