OBD-II trouble code
P0160: O2 Sensor Circuit No Activity Detected (Bank 2, Sensor 2)
The downstream oxygen sensor on bank 2 isn't producing any signal — the voltage is flat or stuck at a single value. Same failure mode as P0140, but on the cylinder bank that does not contain cylinder 1, with the same bank-2 labor premium.
Quick facts
- System
- Powertrain
- Category
- Oxygen Sensor
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $5 – $600
- DIY difficulty
- Intermediate DIY
Browse every code in P0100–P0199, or start from the full code library.
What does P0160 mean?
P0160 is the bank-2 mirror of P0140, and the diagnostic question that matters most is the same one you'd ask on bank 1: is the sensor dead, or is the wiring dead? Both produce the same code, but they cost very different amounts to fix and have very different repair paths. A dead sensor means a $150-450 replacement (a bit more on bank 2 because of access). A wiring or fuse problem can be anywhere from a $5 fuse to a $500 harness repair — usually less than a sensor swap when it turns out to be a simple wiring issue.
The bank-2 access premium applies here as it does on P0156 — but check which bank is which before assuming where the work is. Bank 2 is whichever bank does not contain cylinder 1, and that is not a fixed side: on Toyota's 2GR-FE, for instance, bank 2 is the front bank facing the radiator rather than the firewall one, while on other transverse V6s it is the reverse. Where bank 2 does turn out to be the firewall-side bank, the downstream sensor is tucked between the catalytic converter and the transmission. Reaching it usually means working blind from underneath the vehicle in a hot and tight space. Even when the part costs the same as the bank-1 equivalent, the labor estimate typically runs 30-60% higher. Build that into your expectations before getting a shop quote — a P0156/P0160 repair that looks identical to a P0136/P0140 fix on paper will come in higher.
The failure modes are the same as P0140: a dead sensor, a wiring or fuse problem, and a smaller group involving heater failures or catalyst contamination. Because P0160 doesn't affect fuel trim, the symptom profile is subtle — Check Engine Light, slight fuel economy drop, failed emissions readiness, no major driveability complaint. That subtle profile is why these codes often go unnoticed until a smog inspection.
Common causes
- Blown O2 sensor heater fuse, sometimes shared across several sensors — under $5 and the first thing to check
- Broken or backed-out pin at the bank-2 sensor connector
- Corroded sensor connector preventing reliable signal return
- Open circuit in the signal wire between the bank-2 downstream sensor and the PCM
- Failed bank-2 downstream O2 sensor — dead sensing element or completely failed heater
- Failed heater inside the sensor (often sets P0161 alongside P0160)
- Chafed or melted wiring near the bank-2 catalytic converter heat shield
- Corroded sensor connector preventing reliable signal return
- PCM driver circuit failure (rare)
Symptoms
- Check Engine Light on
- Slight loss of fuel economy
- Failed emissions test or emissions readiness not complete
- Catalyst monitor not ready on a smog check
- No noticeable change in power, idle quality, or driveability
- Faint exhaust smell on cold start if a heater issue is preventing warm-up
Diagnostic steps
- 1.Pull all current and pending codes. P0160 alongside P0161 means the heater circuit is the underlying issue — fix that first.
- 2.Read live data for bank-2 sensor-2 voltage. A reading stuck at one value (e.g., 0.0V or 0.45V) that doesn't move when engine state changes confirms the 'no activity' fault.
- 3.Before going underneath, put the vehicle on a lift or on axle stands on level ground with the wheels chocked, and let the exhaust cool. This sensor sits against the catalytic converter, which is the hottest thing under the car, and the access this code is known for means working close to it.
- 4.Inspect the bank-2 sensor connector for oil, coolant, corrosion, backed-out pins, or melted insulation.
- 5.Check the O2 sensor heater fuse (often in the underhood fuse box, sometimes shared with bank 1). Sub-$5 fix when it's the cause.
- 6.Disconnect the sensor and measure heater terminal resistance. Most spec 4-15 ohms; open or way out of range means dead sensor.
- 7.Backprobe the harness with key on, engine off — battery voltage should be present on the heater supply pin. If missing, work upstream from the connector.
- 8.Swap-test against the bank-1 downstream sensor (if same part number) to confirm the diagnosis. If the fault follows the sensor to bank 1 (causing P0140), the sensor is bad.
- 9.If wiring tests clean and the sensor checks good, scope the PCM signal path to rule out a module-side issue.
Repair cost
$5 – $600
Blown heater fuse fix: under $5. Bank-2 downstream O2 sensor replacement typically $200-450 — about $50-100 more than bank 1 because of access. Wiring repair: $50-500 depending on damage. If the issue traces to a catalyst that's contaminated the sensor on its way out, costs jump to $500-2,500, but that's less common with no-activity codes than with low-voltage ones.
Estimate your repair
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Open the Repair Cost Estimator with oxygen sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
Related repairs
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.