P0160 = O2 Sensor Circuit No Activity Detected (Bank 2, Sensor 2).

This is a downstream oxygen sensor fault, after the catalytic converter on Bank 2.

What the ECU is Seeing

The ECU expects slow voltage changes from B2S2 (typically 0.1–0.9 V)

With P0160, the signal is flat, stuck, or missing

ECU decides the sensor is inactive or electrically dead

Most Common Causes (in order)

1. Failed O2 sensor (most common)

2. Broken or shorted wiring near exhaust

3. Poor ground or reference voltage

4. Exhaust leak before the sensor

5. PCM issue (rare)

Step-by-Step Diagnostic Process

1. Confirm Live Data (Very Important

Use scan tool:

Engine warm

Look at B2S2 voltage

Normal: slow movement ~0.6–0.8V

Faulty:

Flat at 0.0V

Flat at ~0.45V

No response when revving

👉 If flat → continue testing

2. Visual Inspection (Quick Win)

Check:

Melted wires near exhaust

Sensor connector corrosion

Harness pulled tight or broken

⚠️ Bank 2 is the side without cylinder #1

3. Heater Circuit Check (Very Common Failure)

Key ON, engine OFF:

Check heater power (usually 12V)

Check heater ground

Typical heater resistance: 5–14 ohms

❌ Open heater = sensor replacement

4. Signal Circuit Test

Back-probe signal wire:

You should see ~0.45V reference

Start engine, snap throttle

No voltage movement = bad sensor or open signal wire

5. Exhaust Leak Check

Leak before B2S2 can cause inactivity

Especially cracked flange or gasket after cat

When to Replace the Sensor

Replace Bank 2 Sensor 2 if:

Heater circuit is open

Signal stays flat with good wiring

Live data shows no activity after warm-up

✅ Use OEM or high-quality aftermarket

Cheap sensors cause repeat comebacks

Customer Explanation (Simple)

> “The oxygen sensor after the catalytic converter on one side of the engine is no longer sending a signal to the computer. This affects emissions monitoring and can cause inspection failure.”

Flat Rate Estimate (Typical)

Diagnosis: 0.5 hr

Sensor replacement: 0.5–1.0 hr

Part cost: varies by vehicle

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