1997 02 sensor problem- please help

[jrey1717]

Hi,

Just wanted to check with you guys in regards to an 02 sensor problem i have.

i have a 1997 QX4, and recently replaced the exhaust system. I was working with a local mechanic, and he did the 02 sensors. ( I replaced both downstream using Bosch sensors I got from advance)

When he cleared the codes, the check engine light was off, but as soon as i shut the truck off and started it back up, bam engine light throwing codes for the sensors we replaced.

I called the dealer and they want 110 for a diag, then 225 a piece for the sensors, then another 110 for the "flash" to the computer to update it to take the sensors. He said they have alot of problems with the sensors and it is generally corrected with the factory parts and flash. The parts I got off advance were OEM exact replacements and did not require a splice.

Does anyone have an opinion in regards to this. Do you think I just need a "flash" or I should take out the sensors and replace the with dealer ones. I can't belive the for those two sensors they want 450 in parts and 110 dollars for the diag and then the flash after.


Any input at this point helps, so far ive done trailing arm bushings, alternator, distributor, tire, brakes, shocks, headlamps, complete exhaust, and i had the timing belt snap 3 weeks after i bought it. Needless to say with a newborn baby in january I am getting tired of throwing away money we really need.

Thank you,

Jeff

[4xq]

I'm assuming there were no codes before you did the exhaust work, correct? If you were having problems before the exhaust work, please post the codes. Wouldn't hurt to post the codes you are getting now.

My first suspicion would be you somehow have the sensors swapped and installed on the wrong side. I don't know this for a fact, but I would check whether the wiring pinouts are different for each side. You can find that in the service manual I believe.

If your mechanic has a graphing scan tool, he should be able to look at the activity on the downstream sensors. If the wiring in each sides plug is different, they will probably look dead on the graph (flat line) assuming they are reversed. That would be confirmation to me there is a wiring problem.

No reason your aftermarket sensors will not work. Its just a matter of figuring out why you now have a problem. I'm using aftermarket sensors in my 02 Qx4 - they work fine. No flash should be necessary.

[4xq]

Oh, I should also mention : If there is a wiring problem he may get "no data" or "can't connect" when he trys to scan those sensors.

[jrey1717]

Okay, got the codes. At first I bought the upstream ones, he had already removed the downstream sensors, so he capped the pipes where the sensors went, and at that point it was the first time the check engine light came on. There was no check engine light on when i began replacing the exhaust.

I drove it for about a week, about 15 miles a day to and from work, while we waited on the new sensors. He tried to use his hi tech scan tool and it would not connect. We went back to the good old orange one and it connected. He cleared the codes and as soon as you turn of the ignition, and start the car up the check engine light comes on immediately.

To allieviate your concern of them being crossed, the wires are only so long for each sensor, and wouldn't reach to switch them. We thought of that at the garage and gave it a shot.

The codes I have are :


P0325 Knock Sensor

All O2 codes:

P0135 1-1
P0141 1-2
P0155 2-1
P0161 2-2


Please help, i really dont want to have to take this to the dealer for another 800 dollars.

Thank you,

Jeff