Honda DTC P1166 – Primary HO2S (No. 1) Heater System Electrical
DTC P1166 meaning on Honda
DTC P1166 on a Honda refers to the Primary HO2S (No. 1) Heater System Electrical. This diagnostic trouble code indicates an issue with the electrical circuit of the primary heated oxygen sensor (HO2S) in bank 1 of the engine.
Honda DTC P1166 symptoms
Symptoms of DTC P1166 on a Honda may include:
- Check Engine Light (MIL) illuminated
- Decreased fuel efficiency
- Engine running rough or misfiring
Honda DTC P1166 causes
Common causes of DTC P1166 on a Honda include:
- Failed primary HO2S (No. 1)
- Wiring or connector issues in the HO2S circuit
- Faulty engine control module (ECM)
Honda DTC P1166 seriousness
DTC P1166 should not be ignored as it can lead to poor engine performance and increased emissions. It is important to address this issue promptly to prevent further damage to the vehicle.
How to diagnose DTC P1166 on Honda
To diagnose DTC P1166 on a Honda, a mechanic may perform the following steps:
- Use a scan tool to retrieve the DTC and freeze frame data
- Inspect the primary HO2S (No. 1) and its wiring for any visible damage
- Check the HO2S heater circuit for continuity and proper voltage
- Test the ECM for proper operation
How to fix DTC P1166 on Honda
To fix DTC P1166 on a Honda, the following steps may be taken:
- Replace the primary HO2S (No. 1) if faulty
- Repair any damaged wiring or connectors in the HO2S circuit
- If the ECM is determined to be faulty, replace or reprogram it
How to erase DTC P1166 on Honda
To erase DTC P1166 on a Honda, the code can be cleared using a scan tool that has the capability to reset fault codes. Once the issue has been addressed and fixed, the code can be cleared to turn off the Check Engine Light.
Recommended tools for Honda diagnostics
Explore our expert picks: The Best OBD2 Scanners for 2025
Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter
Some of the links on this page may be affiliate links, which means we may earn a small commission if you make a purchase. This helps us keep our DTC database up to date and provide valuable content for free. We only recommend products that we have tested and believe to be the best in their class.