Batman

I have a 97 E320 with about 106k miles and the check engine light came on. The car was running a little rough. Drove it the next day for a little bit and it drove fine (check engine light was still on though).



OBDII Codes:

P0131
O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)

P0302
Cylinder 2 Misfire Detected

So, I'm guessing it's the oxygen sensor (the first one). Sound right?

My next question is, should I get a new sensor (if that's what the problem is) from the dealer for $204 (I might be able to get 20% off) or should I get the Bosch OE sensor for $135 at Autozone or the Bosch Universal sensor for $92 from Autozone (I might be able to get these cheaper at another local parts store)??

Also, should I change the spark plugs at the same time?
plugs from dealer or Bosch?

Or should I just reset the check engine light and see what happens?

Thanks

mleskovar

I'm no expert and have never used an OBD tester but I'm thinking of getting one. I believe an advantage to having your own tester is the ability to reset the light. Then you can see if it comes back with the same code or not. From what I've read about the CEL some transient problems can set it off. Did you buy your own OBDII tester? What kind and how much? I've seen them for as liitlle as $50.

Batman

I didn't buy my own tester, I had the codes checked for free at a local parts store. But, I was thinking about getting a pocket pc and I was looking in to seeing what was available for that.

But, back to the topic at hand. I would like to order the part tomorrow if possible (if stores are even open). Or, should I try to clear the code first and see if it comes back? I didn't want to drive around with something wrong and cause damage that I could have easily prevented. I'd really like a techs opinion on this one.

Thanks

Petmerctech

If they are the original O2 sensors, I would go ahead and replace them anyway, considering the mileage on your car. I would also check the voltage supply to the O2 sensor. As for the misfire, check the spark plug wire for #2 cylinder. Also, pull the spark plug in the #2 cylinder and check the condion and gap.

moebisgold

I second that! Exactly what I would do. Buy the Bosch $ one. It's not much more and it will fit exactly the same as OE. I put new ones in at 97 k and it started running better instantly. Especially on the transition from open to closed loop when cold. Maybe it's time for a tune up any way? Plugs and wires and...

Batman

Thanks for the replies. My dad is the primary driver of the car and he mentioned something about this starting after he got gas the other day. So, I had him take the gas cap off and make sure he put it on correctly and the light went away and the car is driving fine.

But, when you say buy the Bosch Sensor, which one do you mean? The OE Bosch or the Universal Bosch?

Another question. I hear different answers to this all the time. Oxygen sensors. Do they either work or not (like a light bulb)? OR, can they degrade and have poor performance, but still "function" without causing a check engine light to come on? From what I've read, it seems like they can degrade. If that's the case, can they be cleaned (I know it's probably not worth it, but I just wanted to know if that would work)?

Petmerctech

O2 sensors degrade over time and usage and when they do, they cause poor fuel economy. After a while, they start to respond slowly which gives false/delayed information to the ECU as to how much fuel to inject. But this is after tens of thousands of miles of driving. The usual life of an O2 sensor is about 60,000 to 80,000 miles.

moebisgold

"But, when you say buy the Bosch Sensor, which one do you mean? The OE Bosch or the Universal Bosch?"
OE, its just a couple $ more.

Batman

Thanks again for the info guys. Mleskovar, those are some crazy rims. Have any more pics of your car?

Batman

Well, I've replaced the spark plugs, and the O2 sensors. (changing the O2 sensors was not fun. I took the whole exhaust off to get to the top sensor. I also had to clean the threading on the top one because the new sensor wasn't going in easily). Car still ran the same and then I got another P0302 Check Engine Code (cylinder 2 misfire). When I was changing the plugs, I noticed the cylinder 2 plug was in bad shape compared to the others. So, I'll be changing the spark plug wires on Monday. $85 for the Bosch wires. $200 for the ones from the dealer. I'm getting the Bosch wires. If that doesn't fix it, my next guess would be the coil packs, right?

The car seems to drive fine at speed, but when coming to a stop in drive, it idles rough. It seems to be fine at a stop if I put it in neutral.

I spoke to a tech at the dealer and he said it was probably the throttle motor ($1100). I doubt that's what it is. Any second opinions on that?

Thanks.

Batman

I put new bosch spark plug wires in and everything works fine now. thanks for the input.

GrepAwk

Could you see any obvious cracks in the plug wires that might have caused the missfires in cyclindar 2?

Batman

Not really. But then again, I didn't look closely as it was pretty late at night and I was just glad it worked.

teky

the 2 codes you mention are one fault and its not the o2 sensors, its probably the MAF (mass air flow sensor) then multi plug pins get dirty/short out and cause bad info to the ecu hence you get a bad burn on start up and causes a lean mixture which inturn logs those tipical fault codes, the maf sensor makes the engine run rough ( also the idle control valve ) clean both up and rest the ecu then try it