99 S70 GLT : P0134 O2 Sensor + P0301 Misfire

Thames · Post by **Thames** » 23 Sep 2013, 09:47

Hi pals,

This weekend my S70 started running rough @ idle.
So I took the code reader and got a P0134 O2 Sensor no activity Bank 1 Sensor 1.
I was about to order the correct replacement (Bosch 15667), so I read the code again this morning, and now the "P0301 Cylinder 1 Misfire" code just appeared.

Could this new code is due to the misfiring caused by the bad O2 sensor ?

Car has 170K KM, top notch condition, running 91 octane gas (Quebec, Canada).

Post by **JDS60R** » 23 Sep 2013, 10:02

Yes- replace the sensor first and quickly. Continued misfiring can destroy the catalytic converter quite quickly.

Post by **E Showell** » 24 Sep 2013, 11:07

Prolonged running with a bad sensor may also cause a lean running condition which can lead to burned valves which mean either a cylinder head repair (pricey) an engine swap (also pricey) or a viking funeral (unfortunate). Don't mess with this one. Replace right away.

Thames · Post by **Thames** » 21 Oct 2013, 11:57

OK gents.
So I had my front 02 sensor replaced by the correct one, a Bosch wideband 02 #15667.

Car ran fine, except that my mechanic had some hard time removing the original one, so I think he put some stress on the exhaust line as I now have a leak at the joint, right after the catalytic converter.

I drove the car for a about a week with this leak (not too noisy but noticeable), it slowly became noisier, then I got similar O2 problem again, I got some various codes, I clear'd them to see if they'd come back, nothing since but now I have the P0134 back again ( I should have noted these other codes...).

Any idea ? I'll try to check with a VIDA software to find the culprit...

Thames · Post by **Thames** » 23 Oct 2013, 07:56

OK. Yesterday I cleaned my MAF sensor just in case. The car seems to run fine, except that I now have a P1133 code... ??!

Post by **osman** » 23 Oct 2013, 08:12

Oxygen sensor codes are usually caused by vacuum leaks or a rich or lean running condition I never replace O2 sensors without testing them first. Torque app offers the ability to see the o2 sensor waveforms in real time, something that only expensive scanners do.

Thames · Post by **Thames** » 24 Oct 2013, 09:52

Great. Do we have any clue on common vaccum leaks ?

loub · Post by **loub** » 24 Oct 2013, 20:02

According to my library automotive diagnostic website a leaking or restrictive exhaust system can trigger a P0134. code.

Thames · Post by **Thames** » 21 May 2014, 10:45

Well.. 8 months later.

The same code came back yesterday !

I know I have a leak right before the muffler this time, I'll patch and reset the code. Will let you know.

Thames · Post by **Thames** » 04 Sep 2014, 11:35

Still having the same issue...