S70 2000 - Help with some error codes

Gatekeeper21 · Post by **Gatekeeper21** » 06 Jan 2010, 12:42

I am not currently having any problems, but just want to get the check engine light off if possible. I am getting the following codes:

p0135 - O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
p0463 - Fuel Level Sensor Circuit High Input

I am not certain where to find the O2 sensor. Would cleaning the sensor possibly solve the problem or does it just need to be replaced?

I have not found much information about the other code, I really have no clue what it means.

Thanks much

Post by **Ozark Lee** » 06 Jan 2010, 15:06

Cleaning an O-2 sensor rarely works and with your code it indicates the heater circuit is open. That could be a dirty connection but likely the heater just burned out. The heater is much like a light bulb only hotter.

Does your fuel gauge work? If so just clear that one and see if it comes back.

...Lee

volvslow · Post by **volvslow** » 06 Jan 2010, 17:48

o2 code is probably the o2 sensor itself. although the wiring could be the issue its more common to be a fault in the sensor. as for the fuel gauge-change the location of where you buy gas(ie...switch from racetrac to bp or what have you) cheap fuel can cause a build up of corrosion on the fuel level sender unit. also run some mild injector cleaner through the tank. should clean off the sender unit. dont use cheap stuff like stp ect... check with your volvo dealer to see what they approve. i use bg oil products. which is approved and used by most dealers

Gatekeeper21 · Post by **Gatekeeper21** » 06 Jan 2010, 19:57

The fuel gauge is working fine, although the gas light goes off and on when the tank is low (been doing that for a while). I will try running some cleaner through and see if that takes care of it. I have already cleared it once, but it just came right back on.

I'm assuming that even if it is the heater of the o2 sensor, I still need replace the entire unit? What is the purpose of this sensor? I don't notice anything strange about the driving, so it is hard for me to understand paying 200 dollars for a new part if nothing is going to change.

Thanks again

Post by **confused_al** » 06 Jan 2010, 20:09

Gatekeeper21 wrote:I am not certain where to find the O2 sensor.

FYI
https://www.matthewsvolvosite.com/forums ... =1&t=24698

Post by **Ozark Lee** » 06 Jan 2010, 21:47

I still need replace the entire unit? What is the purpose of this sensor?

If the heater is bad the entire sensor must be replaced to make the system happy again. The O2 sensor, combined with the MAF sensor and other sensors, determines the fuel mixture on the car for optimum performance and the lowest emissions. The O2 sensor has a lot of weight in the calculations.

The firmware in the ECU has limp home modes built in so as to not strand you on the side of the road when most of the sensors fail but the substitute values (guesses) are far less efficient than a properly working system.

Your mileage will suck but in most cases you can get by with a bad O2 sensor. There are cases where you will run too rich and it will eventually cook the catalytic converter.

...Lee

Gatekeeper21 · Post by **Gatekeeper21** » 07 Jan 2010, 05:54

I did notice on the way in this morning that my mpg has decreased by 3, so I guess this is something worth doing soon. Wasting money on gas is definitely not worth it, especially if it may end up burning out the cat. Thanks for the link above, I found the part on Amazon for almost half the price I could find it elsewhere.

Gatekeeper21 · Post by **Gatekeeper21** » 07 Jan 2010, 08:35

Just to make sure, this is the o2 sensor before the catalytic converter, right?

Btw, I typically stick with good gas (sunoco, 76, bp, etc) to try to prevent anything like this from happening. I will still run some cleaner through and see if takes care of it. The only stuff I have run through over the last few years is stp, so I will definitely find something a step up.

Gatekeeper21 · Post by **Gatekeeper21** » 07 Jan 2010, 18:18

I just thought of something. A couple weeks ago, a hole formed in my power steering pressure hose. My entire engine bay is currently coated in power steering fluid (looks nice and shiny at least). Is is possible that this caused the sensor to short and cleaning the wiring may fix the issue? Not sure if that is something that could be caused by power steering fluid. Where exactly do I find the o2 sensor and connector? I see a wiring harness in between the engine and fan that I think may be it, but I am not certain. Won't have enough light to look around under the car until this weekend, so I am just trying to figure everything out so I can get it done.

Post by **misha** » 07 Jan 2010, 18:26

If you're going to buy new o2 sensor,buy ONLY oem Bosch o2 sensor.These cars don't love generic electronic parts.

So...read the Bosch number from your old o2 sensor and buy a new one with exactly the same Bosch number.