| Author | Message | ||
     Dennis_c |
ON the IC in diag mode with the motor not running the frt 02 sensor said 0.4 voltage rear voltage 02 sensor 0.4 both the same. With motor at normal operating temperature with motor running the frt 02 sensor stayed at 0.4 volts the rear 02 sensor went from 0.1 to 0.8 volts back and forth random numbers constantly is this normal? Can any one with a 1125 see what thers does. | ||
| Panshovevo |
I can't help with what one normally does, as my CR is slowly getting an engine swap and the R, which is running (just not ridable at the moment) doesn't have the stock sensors installed. However, it sounds to me like you have a problem with the front sensor. For it to read the same voltage with the engine running and at operating temp, as it does with the engine cold and not running tells me there is a problem. They use voltage to indicate the amount of unburned oxygen in the exhaust. I'll take a look at the Electrical Diagnostic manual, and refresh my memory on how to test them. Are you getting any trouble codes? | ||
| Dennis_c |
no on o2 sensor | ||
| S21125r |
Any codes present? Your rear sensor is acting normally but the front one isn't. Narrow band O2 sensors only know 2 states - lean and rich. In closed loop mode the ECM adds fuel until the O2 shows rich (above ~.5 V) and then takes away fuel until the O2 shows lean (below ~.5V). This ping pong routine keeps the Air/Fuel Ratio "close enough" to Stoich. If the sensor isn't oscillating then it's not working and the ECM is probably using open loop fuel values to set the injector pulse width. Unplug the sensor and get a volt meter attached - usually there is a hot and ground wire for the O2 heater circuit that you can check continuity on and then the 3rd wire will be the 0-1V signal wire. Usually not a ground wire for the signal as it's grounded through the sensor body -> exhaust manifold -> engine -> chassis/battery. If the heater circuit is bad then it will never get up to temp and the ECM will ignore - chances are it will set a code and Check Engine Light. If you have a break in the signal wire, or a bad ground then the ECM will ignore and also set a code and CEL. | ||
| Stevel |
Good explanation of a narrow band O2 sensor. Interestingly, the ECM driver of the heaters is J2 pin 23 with ground on pin 24. This driver is a shared driver and also supplies power to the starter relay on J2 pin 7. I do not know what pin goes to what at the O2 sensors, but if the wire is open, you would experience the same symptom as a bad sensor. | ||
| Dennis_c |
It was the frt 02 sensor I had 6 codes but no 02 sensor code now no codes  |
