Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
P0161 2/2 O2 Sensor Heater Failure
1999 Chrysler 300M V6-3.5L VIN GSECTION P0161 2/2 O2 Sensor Heater Failure
NAME OF CODE
O2 Sensor Heater Failure
WHEN MONITORED
The O2 Heater Monitor runs during O2 sensor cool-down period, after a hot drive cycle, when engine is shut-down with the ignition key turned "OFF".
SET CONDITION
Using O2 sensor signal voltage readings, during O2 sensor cool-down period, with heater OFF compared to O2 sensor signal voltage with heater ON.
THEORY OF OPERATION
The oxygen sensor is a voltage generating device. The PCM receives exhaust gas information from this O2 sensor. The sensor detects exhaust gas content by a galvanic reaction within the sensor that produces a voltage. After measuring the amount of oxygen in the exhaust gases. This O2 sensor serves as an indicator of oxygen content. The heater element helps the O2 sensor quickly reach a normal and steady operating temperature, which is required for proper emission control.
POSSIBLE CAUSES
- Open heater element circuit
- O2 sensor failure
- O2 heater wiring
- Powertrain control module failure
- Connector terminals
- Connector wires
- ASD Fuse(s)
- Open ASD Relay Circuit
O2 Sensor Heater Failure
WHEN MONITORED
The O2 Heater Monitor runs during O2 sensor cool-down period, after a hot drive cycle, when engine is shut-down with the ignition key turned "OFF".
SET CONDITION
Using O2 sensor signal voltage readings, during O2 sensor cool-down period, with heater OFF compared to O2 sensor signal voltage with heater ON.
THEORY OF OPERATION
The oxygen sensor is a voltage generating device. The PCM receives exhaust gas information from this O2 sensor. The sensor detects exhaust gas content by a galvanic reaction within the sensor that produces a voltage. After measuring the amount of oxygen in the exhaust gases. This O2 sensor serves as an indicator of oxygen content. The heater element helps the O2 sensor quickly reach a normal and steady operating temperature, which is required for proper emission control.
POSSIBLE CAUSES
- Open heater element circuit
- O2 sensor failure
- O2 heater wiring
- Powertrain control module failure
- Connector terminals
- Connector wires
- ASD Fuse(s)
- Open ASD Relay Circuit
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.