{"id":243164,"date":"2023-10-26T11:49:11","date_gmt":"2023-10-26T11:49:11","guid":{"rendered":"https:\/\/automotobuzz.com\/?p=243164"},"modified":"2023-10-26T11:49:11","modified_gmt":"2023-10-26T11:49:11","slug":"my-gixxer-sf250-issues-found-reasons-after-o2-sensor-self-diagnosis","status":"publish","type":"post","link":"https:\/\/automotobuzz.com\/news-features\/my-gixxer-sf250-issues-found-reasons-after-o2-sensor-self-diagnosis\/","title":{"rendered":"My Gixxer SF250 issues: Found reasons after O2 sensor self diagnosis"},"content":{"rendered":"

According to the manual, the voltage reading should be between 0-1v at idle. <\/h2>\n

BHPian b16h22<\/strong> recently shared this with other enthusiasts.<\/p>\n

I have an idle hunting issue when the bike is warmed up, so I decided to diagnose my O2 sensor. And the diagnosis was very interesting. I might’ve found the reason for my engine’s poor running and vibes once it was warmed up<\/p>\n

O2 Sensor diagnosis:<\/h2>\n

The O2 sensor is placed on the exhaust right before the cat. There is only one. You can find the connector that goes to the ECU right behind the bottom side panel that covers the frame, among other wires. Unclipped the connector and there were 4 terminals.<\/p>\n

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This is the layout of the O2 sensor connector I got from a Spanish Gixxer 250 service manual. Google translate was of great help.<\/p>\n

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First two terminals give you the voltage output from the sensor. This is what ECU reads and uses to adapt the AFR in closed loop fuelling. The bottom two terminals are for the heater element inside the sensor. You can also spot them by looking for two similar colored cables coming to the sensor among the 4 that is on there. It was black colored on the Gixxer.<\/p>\n

Voltage readings:<\/h2>\n

According to the manual, the voltage reading should be between 0-1v at idle. And it should fluctuate. Voltage reading I got was 0.00V initially and it increased to 0.02V a minute later but it stayed there without any change Even when I revved the engine to 4-5k rpms, the voltage reading was not changing at all.<\/p>\n

Heater element resistance readings:<\/h2>\n

The manual says the resistance between bottom two terminals should be between 5.49-6.91 ohms<\/p>\n

<\/p>\n

The reading I got after multiple checks was 9.0 ohm. Again not in the range<\/p>\n

Observations after disconnecting the O2 sensor:<\/h2>\n

Disconnecting the O2 sensor basically puts the bike into open loop fuelling mode always. Open loop fuelling works off the default fuel maps coded into the ECU. It doesn’t read the o2 sensor values and adapt the fuelling to AFR values that is required for the emission norms and economy. It basically runs a richer map.<\/p>\n

It also lights up an engine malfunction light along with an FI error on the console. Because the ECU looks for the sensor and since it cannot read the signal anymore, it throws a check engine light. This can also happen if your sensor has completely failed. From what I’ve understood, if the heating element has not failed, it won’t show a CEL. O2 sensor delete and dongles that trick the ECU into thinking the sensor is still there are popular among aftermarket tuning crowd.<\/p>\n

So my bike is now stuck in open loop fuelling after disconnecting the O2 sensor.<\/p>\n