A failed heated oxygen sensor (HO2S) itself, where the sensing element is contaminated or degraded and cannot generate a proper voltage signal.; A short to ground or chafed wire in the sensor signal circuit between the sensor and the PCM, often near the exhaust manifold or under the hood.; Corroded or loose electrical connector pins at the sensor or PCM, causing high resistance and a low voltage reading.; An exhaust leak before the sensor, allowing outside air to reach the sensor and produce a false lean (low voltage) signal.; A faulty PCM driver or internal circuit, though this is rare and should only be suspected after all other possibilities are ruled out.; Low fuel pressure or a vacuum leak causing an actual lean condition that the sensor correctly reports as low voltage.

DTC codes / Honda codes / P1168

P1168 · HondaHO2S11 Label Circuit Low Voltage Fault Bank 1 Sensor 1

Q: What does code P1168 mean?

HO2S11 Label Circuit Low Voltage Fault Bank 1 Sensor 1. P1168 on Honda vehicles means the powertrain control module has detected a low voltage condition on the signal circuit for the primary heated oxygen sensor, bank 1 sensor 1, which is the sensor before the catalytic converter. The computer monitors the sensor's output and sees a voltage that stays below the expected threshold for too long, indicating a lean signal or a circuit fault.

P1168 on Honda vehicles means the powertrain control module has detected a low voltage condition on the signal circuit for the primary heated oxygen sensor, bank 1 sensor 1, which is the sensor before the catalytic converter. The computer monitors the sensor's output and sees a voltage that stays below the expected threshold for too long, indicating a lean signal or a circuit fault.

SystemPowertrain

Code typeHonda specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Check engine light illuminated, often with no other noticeable symptoms.
Rough idle or stumbling when the engine is cold, especially during open-loop operation.
Poor fuel economy as the computer may default to a rich fuel mixture.
Hesitation or a slight surge during light acceleration.
In some cases, a failed emissions test due to increased hydrocarbons or carbon monoxide.
Rarely, the engine may stall or run poorly enough to trigger a misfire code.

Common causes, most likely first

A failed heated oxygen sensor (HO2S) itself, where the sensing element is contaminated or degraded and cannot generate a proper voltage signal.
A short to ground or chafed wire in the sensor signal circuit between the sensor and the PCM, often near the exhaust manifold or under the hood.
Corroded or loose electrical connector pins at the sensor or PCM, causing high resistance and a low voltage reading.
An exhaust leak before the sensor, allowing outside air to reach the sensor and produce a false lean (low voltage) signal.
A faulty PCM driver or internal circuit, though this is rare and should only be suspected after all other possibilities are ruled out.
Low fuel pressure or a vacuum leak causing an actual lean condition that the sensor correctly reports as low voltage.

How to diagnose and fix it

Inspect the HO2S11 sensor and its wiring for obvious damage, corrosion, or loose connectors, and repair any faults found.
Check for exhaust leaks between the cylinder head and the sensor using a smoke machine or by listening for ticking noises when cold.
Measure the sensor's signal voltage with a scan tool or oscilloscope while the engine is running; a properly working sensor should switch rapidly between 0.1V and 0.9V.
Perform a voltage drop test on the sensor signal circuit and ground circuit to rule out high resistance in the wiring.
If the sensor is slow to respond or stuck low, replace the HO2S11 with a quality direct-fit sensor.
After replacement, clear the codes and verify the sensor switches properly and the code does not return during a test drive.
If the code persists, check fuel pressure and inspect for vacuum leaks that could cause a genuine lean condition.

What a low HO2S signal really means

A low voltage signal from the oxygen sensor often indicates a lean condition, but it can also be caused by a sensor that is simply old and lazy, unable to generate voltage even when the mixture is correct.
Exhaust leaks upstream of the sensor are a commonly missed cause because they introduce oxygen that the sensor interprets as a lean mixture, setting a low voltage code without any sensor fault.
Technicians sometimes replace the oxygen sensor only to find the connector pins are pushed back or corroded, so always wiggle-test the harness while watching live data.
This code is specific to bank 1 sensor 1, so do not confuse it with downstream sensor codes; the upstream sensor is the primary fuel control sensor and has a much greater effect on driveability.
A contaminated sensor from silicone poisoning or coolant intrusion can set this code without any visible damage, so replacement is often the only reliable fix after circuit checks pass.

Can I keep driving with P1168?

You can usually drive the vehicle with this code, but expect reduced fuel economy and possibly rough running; avoid heavy acceleration or towing until it is repaired, and do not ignore it because prolonged driving with a rich default mixture can damage the catalytic converter.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Honda vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.