Code
P1195
DODGE
P — Powertrain
O2 Sensor 1/1 Bank 1 Sensor 1 Slow During Catalyst Monitor
AI status
Completed
Completed
100%
Causes
- Aging or failing upstream (Bank 1 Sensor 1) oxygen sensor (slow switching)
- Heater circuit fault in the heated O2 sensor (open, short, or no power/ground)
- Damaged wiring or poor connector/ground to the sensor
- Sensor contamination (silicone, oil, lead, fuel additives, coolant)
- Exhaust leak upstream of the sensor
- Fuel system issues causing persistent rich/lean condition (MAF/MAP fault, leaking injector, fuel pressure problem)
Symptoms
- Illuminated MIL / Check Engine Light
- Catalyst monitor fails or won’t set ready
- Poor fuel economy
- Rough idle or hesitation possible if sensor severely degraded
- Failed emissions test (high tailpipe emissions)
- Freeze frame may show specific conditions during failure (load, rpm, temp)
What to check
- Read freeze frame data and stored and pending codes
- Verify engine warmed to normal operating temperature before testing (O2 sensors require heat)
- Inspect sensor connector and wiring for damage, corrosion, or water ingress
- Check for exhaust leaks upstream of Bank 1 Sensor 1 (manifold, flange, gaskets)
- Monitor live O2 sensor voltage with scan tool or oscilloscope while performing snap throttle and steady state to observe switching behavior
- Compare upstream (B1S1) response to downstream sensor and expected narrowband waveform
Signal parameters
- Typical narrowband O2 voltage range: ~0.1–0.9 V (low ≈ lean, high ≈ rich)
- Healthy upstream narrowband sensor should switch/oscillate frequently (~0.5–2 Hz under closed-loop varying conditions) — slow or flat response indicates a problem
- Heater circuit: low resistance expected (varies by manufacturer; commonly a few ohms to a few tens of ohms) — consult Dodge service manual for exact spec
- Heater supply: switched battery voltage or ignition feed present with key on/engine off; PCM command/ground present during operation
- Observe sensor response time to rich/lean condition changes (snap throttle) — delayed rise/fall compared to reference indicates slow sensor
Diagnostic algorithm
- Retrieve DTC(s), freeze frame and clear codes; confirm P1195 returns after a proper drive cycle.
- Visually inspect Bank 1 Sensor 1 connector and wiring for damage, corrosion or poor terminal contact; repair as needed.
- Check for exhaust leaks upstream of sensor; repair any leaks before further testing.
- With engine at operating temperature, monitor B1S1 voltage on a scope or scan tool during snap throttle. Note switching amplitude and frequency and compare to B1S2 or known-good sensor waveform.
- Test heater circuit: measure heater resistance (compare to spec), verify fused power supply and ground/PCM control. Repair open/short wiring or replace sensor if heater defective.
- Review fuel trims, MAF/MAP, and fuel pressure to rule out air/fuel metering issues that could prevent normal sensor switching. Repair underlying issues.
- If wiring and fuel system are good but B1S1 remains slow, replace the upstream O2 sensor with an OE or equivalent heated narrowband sensor.
- After repair, clear codes and perform required drive cycle or EVAP/catalyst readiness cycle to confirm P1195 does not return.
- If replacement does not correct the issue, test PCM outputs/grounds and consider catalytic converter evaluation and PCM software updates as directed by manufacturer.
Likely causes
- Failed or degraded Bank 1 Sensor 1 (slow switching or slow response time)
- Open/short/poor connection in sensor heater circuit or signal circuit
- Contamination coating the sensor element (oil, silicone, antifreeze, leaded fuel residues)
- Exhaust leak upstream of the sensor allowing air ingress
- Fuel trim or air metering fault causing sensor to operate outside normal switching conditions
Fault status
Status
P1195 — O2 Sensor 1/1 Bank 1 Sensor 1 Slow During Catalyst Monitor: Powertrain Control Module detected that the upstream oxygen sensor (Bank 1 Sensor 1) response time is slower than allowed during the catalyst efficiency monitoring routine. This may indicate a slow or faulty sensor, heater/wiring fault, contamination, exhaust leak, or related fuel/PCM issue.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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