RHO2S inversion error after changing o2 sensor

reAper-Hull · 2-14-13, 11:30

Hi all,

I had a problem where i was getting bad idle which when pulling codes was tps and both 23 RHO2S inactivation error and 24 RHO2S inversion error. I changed the tps and the problems went away.

I then decided to put a new o2 sensor in to clear those codes. Since changing the sensor my engine has been acting kinda like its misfiring or hesitating when warm. I pulled the codes again and get 24 RHO2S inversion error. I have new plugs so thought it may be the leads so swapped them but problem still occurs. Does this mean bad o2 sensor? seen as this started happening since the new sensor was fitted..

or has fitting the new sensor made the engine work properly (not in open loop) and highlighted this misfire issue?

Not sure what do to next, maybe put the dodgy old sensor back in lol?

**PaulG** · 2-15-13, 5:49

Sounds like you may have got a bad sensor or it could be another issue, see post 3 here: http://www.mx6.com/forums/2g-mx6-gen...rror-what.html (O2 sensor inversion error? what?)

If the engine is misfiring, it could be a vac leak somewhere. Look/listen for any vac lines that are split, and check the air intake elbow for splits in the plastic after the vaf.

reAper-Hull · 2-15-13, 10:38

thanks for the help: its a tricky one, not sure what to do next wish there was some way of knowing if it is the sensor or my engine running badly, gonna take it to a local tune up place i think and see if they can spot anything, might cost me $$ tho

kentaur · 2-24-13, 6:36

I had similar problem, but the culprit was distributor rotor.
Some of the spark went through the worn out rotor plastic to the camshaft.

reAper-Hull · 2-24-13, 17:04

can this be checked easily? I haven't done any work on my distributor before

reAper-Hull · 2-24-13, 17:10

what should i be looking for to tell the rotor is bad?

kentaur · 3-1-13, 13:49

Plastic around the topside, where the center contact is, looks damaged and discolored.

reAper-Hull · 3-14-13, 11:27

Hi all,

I am a noob so dont flame please

Just noticed that the sensor I replaced is the 4 pin downstream sensor, I didn't realise there are 4 sensors, two upstream (3 pin) and 2 downstream (4 pin) sensors. Does the code 'RHO2S inversion error' relate to the upstream or downstream sensor?

Could this explain why I have hesitation as explained in my first post?

Thanks

**PaulG** · 3-14-13, 12:02

If you're reading codes like 23 and 24, then you have an obd1 car. The obd1 cars don't have 4 sensors, only the 2 upstream sensors on the exhaust manifolds.

reAper-Hull · 3-14-13, 16:02

I have a UK 1996 car, pretty sure its ODB1 as the UK cars are weird, I have to use an LED and wire to pull codes (no CEL) - ok well thats good to know - i checked / cleaned the disty which improved driving slightly but didnt fix the problem, I will order another upstream rear sensor and swap again, hopefully second time lucky

reAper-Hull · 3-14-13, 16:11

can I ask what the 3 wire sensors are for - I belive mine are both 4 wire sensors - does the connector just vary depending on year etc? thanks dude

**PaulG** · 3-14-13, 20:16

Sorry, I didn't realize you were from the UK, I don't know the O2 sensor configuration for the UK cars, but I would guess that it only has the two upstream sensors. You can look under the car to see if you have the two downstream sensors, there should be one before the cat and one after the cat.

In Canada, the Denso site shows the upstream sensors as being 4 wire, but my car (in Canada) only has 3 wire upstream sensors, so that may be an error on their site. My downstream sensors are 4 wire.

I'd be interested to know if you have the downstream sensors, and just confirm if the sensor you changed was in fact a downstream sensor as you said, and if it was 3 or 4 wire.

reAper-Hull · 3-15-13, 5:30

Quote:

Originally Posted by PaulG

Sorry, I didn't realize you were from the UK, I don't know the O2 sensor configuration for the UK cars, but I would guess that it only has the two upstream sensors. You can look under the car to see if you have the two downstream sensors, there should be one before the cat and one after the cat.

In Canada, the Denso site shows the upstream sensors as being 4 wire, but my car (in Canada) only has 3 wire upstream sensors, so that may be an error on their site. My downstream sensors are 4 wire.

I'd be interested to know if you have the downstream sensors, and just confirm if the sensor you changed was in fact a downstream sensor as you said, and if it was 3 or 4 wire.

Do you mean the main cat or the smaller cat's near the exhaust manifold? (if it has them I dont know what it looks like)

The sensor I swapped out was 4 wire, but a mechanic did it for me - doing so removed inactivation code but not the inversion error code - the sensor was just sold as a generic 4 wire sensor

reAper-Hull · 3-15-13, 5:48

Actually is was a pre-cat (upstream?) sensor - see below

I'm starting to think it may be a leak around my exhaust manifold that is causing the inversion error code, is this possible? It has seen better days

Lambda Sensor Mazda 626 B-Serie MX-6 Xedos Hyund Accent | eBay

**PaulG** · 3-15-13, 6:06

I'm talking about the main cat, does yours have the precats?

A leak around the exhaust manifold would probably be audible, I would start by replacing the O2 sensor to see if that solves it. On the North American mx6, the front and rear sensors can be swapped (same connector style), you may want to try that free fix first to see if the problem follows the sensor. Make sure you clear the codes after you swap the sensor. Did you clear the codes after replacing the sensor the first time?