2018 Ram P0131: What It Means & Is It Safe to Drive?
P0131 on the 2018 Ram: O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1). Here's what it means, what usually causes it, what repairs typically cost, and whether it's safe to keep driving.
What this code means
The upstream oxygen sensor on Bank 1 is reporting a voltage signal below the expected range. This can indicate a faulty sensor, a lean condition, or an exhaust leak near the sensor.
Common causes on the 2018 Ram
- Failed upstream oxygen sensor
- Exhaust leak before the sensor
- Lean fuel condition (vacuum leak, weak fuel pressure)
- Damaged sensor wiring or ground
Symptoms
- Check Engine Light
- Poor fuel economy
- Rough idle in some cases
- Failed emissions test
Typical fixes
- Replace upstream oxygen sensor (Bank 1, Sensor 1)
- Locate and fix exhaust leaks
- Smoke test for vacuum leaks
- Check fuel pressure
Repair cost range
For a 2018 Ram, repairs for P0131 typically fall between $100 and $350, depending on the root cause and labor rates in your area.
Known issues on Ram
Ram P0131 upstream O2 sensor Bank 1 typically means a degraded sensor past 80–100k miles. On the HEMI, inspect for a small exhaust manifold leak near the sensor—HEMI exhaust manifold bolts are known to back out and create a leak that triggers false lean readings.
Most commonly affected models