| Author | Message | ||
     Rick Schwiem (Rickinaurora) New Member Username: Rickinaurora Post Number: 7 Registered: 05-2003 |
P1193 Oxygen Sensor Heater Circuit Open Downstream What and where do I start. which sensor is out? | ||
| marc olivares (Pugs) Member Username: Pugs Post Number: 129 Registered: 12-2002 |
rick, first off, were there any other codes stored in your ecu? how many miles on the truck? in brief, a 4 wire O2 sensor has 2 circuits. in the first circuit, the O2 sensors use the heat from the exhaust and the unburned O2 in the pipe to enduce a chemical reaction which inturn produces a voltage (ranging between 100 and 900 millivolts). this is often called the sense and sense return circuit. the sensor makes voltage, sends to the ecu, and the return line completes the circuit back to the source point (the sensor) because heat is necessary for this chemical reaction to take place, a heating circuit was installed to pre-heat the sensor, making it possible for the sensor to respond more quickly with real time information (or voltage) to the ecu. so why is this important? well the faster this happens, the faster the truck goes into closed loop (ie running off sensor data) which lessens the amount of harmful emissions are sent into the atmosphere. so, where do you start? depending on the mileage, i would say the open is in the sensor. meaning that the heating element or resistor has broken within the sensor and is not sending voltage through the sensor and back to the ecu. check the connections on the rear O2 sensors (hense "DOWNSTREAM") if i'm not mistaken, i believe that P1193 is a bank 2 fault code which means that the downstream sensor(downstream of the cat) on the passenger side is your problem. keep in mind that the open can be some where in your wiring loom as well, but chances are it's in the sensor thats where i would start. take an ohms reading off the sensor to check for an open to verify that that is your problem. most O2 sensors should be changed at around 100K. this doesn't mean that people do, but the industry has set a life span of 100k as a replacement cycle. lean run conditions, contaminants (coolant or fumes from rtv sealers) or excess heat will also greatly reduce the lifespan of an O2 sensor hope that helps? marc | ||
| marc olivares (Pugs) Member Username: Pugs Post Number: 130 Registered: 12-2002 |
oh, one other thing, if you wheel the truck and have driven through deep water etc... it could simply be corrosion on the plug. make sure that these connections are clean first. good luck. marc |
