ECU tune detection via the second oxygen sensor
Tags: #diagnostics
To check whether a vehicle has an aftermarket ECU tune, inspect the second oxygen sensor (O2 sensor 2 / ДК2) connector in the engine bay — it sits on the lower left, between the battery and the engine 1. If the connector is unplugged but the dashboard shows no fault codes for O2 sensor 2 or catalyst heating, the vehicle likely has a tune: some tuning firmware removes the second sensor from the ECU's calculations. On an untouched (stock) vehicle, unplugging that sensor would normally trigger a fault code 2. A specialist can confirm definitively by reading the ECU's programming/firmware log.
Related pages
- Oil pressure sensor leak — symptoms and location
- Oxygen sensor — diagnostics and alternatives
- Front oxygen sensor — cost and alternatives
- Odometer/speedometer stops counting — sensor diagnosis
- Clean cylinder-1 piston with coolant loss
Sources
This page is compiled from 2 community messages. Every fact carries a numbered reference to its original author and message.
Last updated: 2026-10-29
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Anonymous user · FAW X80 🚘🛠🛞 · 2024-10-23 · original message · ru ↩
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14 rus (508181919) · FAW X80 🚘🛠🛞 · 2024-11-01 · original message · ru ↩