***If you kept on cranking the motor for long periods of time, you may have burnt the starter motor. He may have been right about that. But I saw no reason for the O2 and fuel level sensors be replaced, if the replacement were done because of the no-start problem. Also, please tell me which O2 sensor that was replaced***
***You may want to ask them (casually). Ask why they suspected the other two O2 sensors need replacing? How come the two O2 sensor didn't come up on their initial diagnostic? What test did they performed to determine that? As they told you that the other two O2 sensors need replacement, exactly which other two? What I am getting at is that you have a total of FOUR O2 sensors. Based on what they were telling you, one would be under the impression that you had 3 O2 sensors.
While bad O2 sensors may cause the ECM to keep the engine in closed loop, therefore will use more fuel (10-15% more) than normal, I am not convinced that the shop perform a thorough diagnostic on your problem.***
***No, it is coincident.***
In a nutshell,
Fuel level sensor: Lets the ECM know how much fuel is in the tank. In some vehicles, based on the fuel level, the ECM can tell the driver the fuel economy data as well as how far the vehicle can travel before a refill.
O2 sensors: Front sensors measure the mixture of the exhaust gas before the catalytic converter. The ECM uses the information to correct the air/fuel ratio for proper fuel economy and emission. Rear sensors check the exhaust gas mixture and its speed to monitor cat efficiency.***
***In worst case scenario, yes. But it is hard to say, really depends on how the vehicle is driven and maintained. The ECM cannot effectively maintain the proper air/fuel ratio, causing lean or rich condition. If lean, the engine will be prone to knocking and/or pinging which will be very bad for the motor. If rich, you will be using too much fuel that will cause EGR and cat malfunction. If there is no MIL statiing bad O2 sensor, I would not replace any of them. If there were MIL (check engine light), then I would replace only the faulty one. It is very unlikely to have 3 sensors bad at the same time. Especially when the shop had already told you that ALL 3 were bad, when you had 4.***
Tuesday, April 7th, 2009 AT 1:25 AM