Question about my check engine light codes

[DSM-Franek]

helloooo

i have a 6 bolt in a 2g with stock 2g 97 ecu and i can't get it "inspected" with the CEL on so i bought a obd2 scanner and this is what it says:

PO170 Fuel Trim Malfunction
PO136 o2 sensor circuit malfunction (Bank 1 sensor 2)
PO141 Downstream Ho2S Heater Failure (m/t)
P1400 Manifold Differential Pressure Sensor Circuit Malfunction

it says i have 8 codes but it just repeats the first 4 again like this

PO170 Fuel Trim Malfunction
PO136 o2 sensor circuit malfunction (Bank 1 sensor 2)
PO141 Downstream Ho2S Heater Failure (m/t)
P1400 Manifold Differential Pressure Sensor Circuit Malfunction
PO170 Fuel Trim Malfunction
PO136 o2 sensor circuit malfunction (Bank 1 sensor 2)
PO141 Downstream Ho2S Heater Failure (m/t)
P1400 Manifold Differential Pressure Sensor Circuit Malfunction

i know the P1400 is because i took my map sensor out but will be putting that back in, but as for the rest of the codes..

can the PO170 be tied into the o2 sensor being bad?

and do both of those o2 sensor codes just mean the sensor is bad? also which is it? when it says sensor 2 im guessing its the one furthest from the turbo?

and for the PO170 my fuel mods are walbro 255 rewired, 660s, afpr set at 45psi with the vacuum line off if that info is needed

any help would be greatly appretiated

Frank

 

[DSM-Franek]

i also have a 3" straight pipe so im pretty sure ill always get a CEL for that right?

is there anything i can do to stop that CEL for AT LEAST 60 miles (that the time period you have to have no CELs to get inspected) ?

 

[cc4ever]

This is cheating, and I might get yelled at for saying this... but take out the LED [It's a light bulb] for the check engine light. It won't make the codes go away though.

 

[Locke]

if they do an OBD-II test, having the light installed or not will make no difference.

 

[DSM-Talon-John]

clear the codes

 

[DSM-Franek]

clear the codes

it wont matter if i take out the CEL light because they do the OBD2 test.. and i can clear the codes but you have to have a minimum 60 miles with no codes to pass inspection and mine comes back on way before that.

is that CEL just from having no cat? or is the sensor bad?

thanks alot

 

[pooker]

You say you bought a 2g with a 6 bolt in it so I am assuming its turbo, what do you mean you took the map out you do not have one of those. I also got a fuel trim malfunction when I had a leak in my intake manifold.

 

[spyderturbo007]

Yes, Bank 1, Sensor 2 is referring to the O2 sensor after the cat. If you don't have a cat, you are going to throw a CEL. The ECU is looking for a consistent voltage from that sensor. If you remove the cat, the ECU is going to see the same "bouncing" voltage from both sensors. It then assumes the cat is not functioning and throws a code.

I'm guessing the rear O2 sensor is still installed in the exhaust? If so, pull it, wrap it in aluminum foil and zip tie it out of the way.

As for the Fuel Trim Malfunction, that is most likely a bad front O2 sensor. Does your scanner allow you to see the ECU's data, or just the CEL's? If you can only view the CEL's, do you have access to a logger?

Also, the MDP sensor CEL could be caused by missing vacuum lines, a failed sensor or a short. You could try taking off the connector and cleaning the terminals if they are corroded. This could also be a problem with the ECU.

It looks like you have a lot of work to do.

 

[DSM-Franek]

Yes, Bank 1, Sensor 2 is referring to the O2 sensor after the cat. If you don't have a cat, you are going to throw a CEL. The ECU is looking for a consistent voltage from that sensor. If you remove the cat, the ECU is going to see the same "bouncing" voltage from both sensors. It then assumes the cat is not functioning and throws a code.

I'm guessing the rear O2 sensor is still installed in the exhaust? If so, pull it, wrap it in aluminum foil and zip tie it out of the way.

As for the Fuel Trim Malfunction, that is most likely a bad front O2 sensor. Does your scanner allow you to see the ECU's data, or just the CEL's? If you can only view the CEL's, do you have access to a logger?

Also, the MDP sensor CEL could be caused by missing vacuum lines, a failed sensor or a short. You could try taking off the connector and cleaning the terminals if they are corroded. This could also be a problem with the ECU.

Yes, the rear o2 sensor is still installed in the exhaust. if I take it out and plug the hole and wrap the sensor in aluminum foil it will stop that CEL?

My scanner just shows the "trouble codes" and I do not have a logger.

When i said i had taken out my map sensor i was refering to the MDP sensor because it was "ghettoly" relocated with a vacuum line glued to the nipple on the sensor. I will put that back in to stop that CEL though.

 

[DSM-Franek]

Also, if i can get away with wrapping it in aluminum foil and plugging the hole, does the second code ( PO141 ) mean the sensor is bad? or is that because of the lack of a cat too?

PO136 o2 sensor circuit malfunction (Bank 1 sensor 2)
PO141 Downstream Ho2S Heater Failure (m/t)

Thanks for the help guys

 

[spyderturbo007]

Our O2 sensors have a heater that brings the O2 sensor up to operating temperature faster than a sensor without a heater. Removing your O2 sensor will show the ECU a constant voltage and essentially trick the ECU into thinking the cat is functioning. You just want to wrap it in Aluminum foil so the heater doesn't catch anything on fire.

Putting your MDP sensor back in will take care of your P1400 CEL. Sometimes these CEL's are tied together and I don't know all of the relationships, but let me look into your other CEL's and see if I can find some possible causes. But for now, I would pull the rear O2, replace the MDP sensor, clear the codes and start driving. That way we can see what comes back and go from there.

EDIT -> Rereading some things here, it almost looks like your rear O2 is shot. Normally the circuit malfunction refers to the ECU seeing a out of tolerance voltage. With a functioning rear O2 and no cat you should get a CEL about catylist efficiency threshold, or something like that. Might want to probe the O2 sensor wire with a voltmeter and see if it's returning a value to the ECU. I'm not sure where you are getting the P0170 CEL from. Normally that's caused by a bad front O2.

 

[DSM-Franek]

Could me being tuned with a safc I cause the PO170? I wouldn't think so but im throwing it out there. I think im going to replace both o2 sensors and see where im at from there.

thanks alot for the help so far!

 

[spyderturbo007]

Yes it most likely is that your SAFC settings are out of wack. I didn't notice that you had a SAFC and no logger.

I would suggest that you pick one up, it would make diagnosing your CEL's much easier. I run the pocketlogger software on a cheap m130 I got from ebay. You can purchase the software here:

www.pocketlogger.com

Last time I checked, it was about $125 for the cable and software.

If you search around, Andy posted a like awhile ago where you could get really cheap OEM O2 sensors. I'll see if I can find the site for you.

EDIT -> Here it is:

www.sparkplugs.com

 

[DSM-Franek]

Wow those are really cheap o2 sensors and they are plug and play

I will look into the www.pocketlogger.com too.

I really appretiate the help so far thanks alot! And I will keep you updated

Thanks Again!
Frank

 

[spyderturbo007]

Wow those are really cheap o2 sensors and they are plug and play

I will look into the www.pocketlogger.com too.

I really appretiate the help so far thanks alot! And I will keep you updated

Thanks Again!
Frank

No problem, Andy posted that link about 3 days after I paid the dealer $130 for mine.

 

[DSM-Franek]

Our O2 sensors have a heater that brings the O2 sensor up to operating temperature faster than a sensor without a heater. Removing your O2 sensor will show the ECU a constant voltage and essentially trick the ECU into thinking the cat is functioning. You just want to wrap it in Aluminum foil so the heater doesn't catch anything on fire.

Putting your MDP sensor back in will take care of your P1400 CEL.

EDIT -> Rereading some things here, it almost looks like your rear O2 is shot. Normally the circuit malfunction refers to the ECU seeing a out of tolerance voltage. With a functioning rear O2 and no cat you should get a CEL about catylist efficiency threshold, or something like that. Might want to probe the O2 sensor wire with a voltmeter and see if it's returning a value to the ECU. I'm not sure where you are getting the P0170 CEL from. Normally that's caused by a bad front O2.

Ok, I took out my rear o2 sensor and wrapped it etc. And plugged the o2 bung in the exhaust with an 18mm oil drain plug

I reset my ecu and let the car idle for about 15 minutes then took her for about a 3 mile ride and only got these CELs back SO FAR.

PO136 o2 sensor circuit malfunction (Bank 1 sensor 2)
PO141 Downstream Ho2S Heater Failure (m/t)

I'm pretty sure the front o2 sensor is shot too though due to how rich ive been running, and thats what caused that "PO170 Fuel Trim Malfunction" I had probably.

Well, its a start .. I will let you know if any more codes come back.

Thanks!
Frank

 

[DSM-Franek]

Ok, so that PO170 is back but im prety sure its from my front o2 sensor. So my codes right now are:

PO170 Fuel Trim Malfunction
PO136 o2 sensor circuit malfunction (Bank 1 sensor 2)
PO141 Downstream Ho2S Heater Failure (m/t)

Any advice would be greatly appretiated!

Thanks!
Frank

 

[spyderturbo007]

I just noticed that you are running 660's......You do have a SAFC or some other tuning device, correct? you should also have a logger to go along with those 660's. If you don't have a SAFC, that is why you are getting the P0170. You FT's are outside the ECU's adjustment limit.

I'm suprised at the P0136 coming back, unless the rear O2 sensor is shot and not providing the ECU any voltage at all. I wish we could get a logger in there. We could have this problem taken care of by now.

Is there anyone near Frank that has a logger he could use for a couple of minutes?????

 

[the_red_pooch]

Wow, this is what I have to look forward to shortly I guess... I also am running a catless apexi turbo-back with my 02 sensors still installed. Is this going to effect my abitlity to tune the car when I get my logging software if I wrap the rear 02 in foil and plug the bung? My CEL has been on since I bought the car and the guy told me it had something to do with the throttle position sensor from the 6-bolt swap but I'm sure theres a whole mess of problems that I have yet to handle. I haven't bought my logging software or anything yet so I can't read my codes, and now I'm a bit scared too . Good luck with the car Frank, I'll probably be coming to you for advice in a few weeks since you seem to have a relatively close setup with a 6-bolt in a 2g and the catless exhaust.

 

[DSM-Franek]

I just noticed that you are running 660's......You do have a SAFC or some other tuning device, correct? you should also have a logger to go along with those 660's. If you don't have a SAFC, that is why you are getting the P0170. You FT's are outside the ECU's adjustment limit.

I'm suprised at the P0136 coming back, unless the rear O2 sensor is shot and not providing the ECU any voltage at all. I wish we could get a logger in there. We could have this problem taken care of by now.

Is there anyone near Frank that has a logger he could use for a couple of minutes?????

I am tuned with a SAFC 1, could that PO136 be from a dead o2 sensor?

I am seeing between .010 and .015 on my SAFC from the rear o2. At WOT at low RPMs and I see above 1v from the front o2 sensor on my SAFC. Im guessing im really rich?
I think im just going to order 2 new o2 sensors somtime this week and see where i'm at with that.

Wow, this is what I have to look forward to shortly I guess... I also am running a catless apexi turbo-back with my 02 sensors still installed. Is this going to effect my abitlity to tune the car when I get my logging software if I wrap the rear 02 in foil and plug the bung? My CEL has been on since I bought the car and the guy told me it had something to do with the throttle position sensor from the 6-bolt swap but I'm sure theres a whole mess of problems that I have yet to handle. I haven't bought my logging software or anything yet so I can't read my codes, and now I'm a bit scared too . Good luck with the car Frank, I'll probably be coming to you for advice in a few weeks since you seem to have a relatively close setup with a 6-bolt in a 2g and the catless exhaust.

, if you have any questions i'll do my best to help you out

-Frank

 

[spyderturbo007]

I am tuned with a SAFC 1, could that PO136 be from a dead o2 sensor?

I am seeing between .010 and .015 on my SAFC from the rear o2. At WOT at low RPMs and I see above 1v from the front o2 sensor on my SAFC. Im guessing im really rich?
I think im just going to order 2 new o2 sensors somtime this week and see where i'm at with that.



, if you have any questions i'll do my best to help you out

-Frank

I'm only familiar with the SAFC-II, so I'm not sure how the SAFC-I displays O2 voltage. I thought the SAFC-I didn't have any readouts? If your decimal is in the correct place, then a voltage of 0.010 means the sensor is dead. That's what I figured when I saw the heater malfunction along with the sensor malfunction.

As for the front sensor throwing the P0170, that is normally the reason you get that code. But if the O2 sensor is showing voltage of 1V at WOT, it's most likely ok, but your tune is bad. It's going to be really hard to get your FT's right without a logger. If I had to guess, I would say that your rear O2 is shot and needs to be replaced. I would also guess that the front sensor is ok, but your tune needs to be adjusted. <- That is my best advice based on what you have told me, but since I can't see the car in person and you don't have a logger, it's hard to say for sure.

I highly suggest that you take back the OBD-II scanner and pick up a logger. It will save you a ton of time and get your car back on track to running properly.

 

[spyderturbo007]

Wow, this is what I have to look forward to shortly I guess... I also am running a catless apexi turbo-back with my 02 sensors still installed. Is this going to effect my abitlity to tune the car when I get my logging software if I wrap the rear 02 in foil and plug the bung? My CEL has been on since I bought the car and the guy told me it had something to do with the throttle position sensor from the 6-bolt swap but I'm sure theres a whole mess of problems that I have yet to handle. I haven't bought my logging software or anything yet so I can't read my codes, and now I'm a bit scared too . Good luck with the car Frank, I'll probably be coming to you for advice in a few weeks since you seem to have a relatively close setup with a 6-bolt in a 2g and the catless exhaust.

No, the rear O2 does nothing except verify that the cat is functioning properly. So that won't cause a problem with your tune.

Your CEL is most likely on becase of the RM (Random Misfire) associated with a 6-bolt in a 2g. But once again, it's hard to say without pulling the codes. It is also possible that he disconnected the TPS in an attempt to get the RM CEL to go away. Do a search for Random Misfire and you will have enough reading for the next 2 weeks.

 

[the_red_pooch]

I think I actually read a big topic a month or so ago about that, wasn't it associated with the cam angle sensor on the 6-bolt and the ecu readings on the 7-bolt? What symptoms would occur from a disconnected TPS?

 

[DSM-Franek]

I'm only familiar with the SAFC-II, so I'm not sure how the SAFC-I displays O2 voltage. I thought the SAFC-I didn't have any readouts? If your decimal is in the correct place, then a voltage of 0.010 means the sensor is dead. That's what I figured when I saw the heater malfunction along with the sensor malfunction.

As for the front sensor throwing the P0170, that is normally the reason you get that code. But if the O2 sensor is showing voltage of 1V at WOT, it's most likely ok, but your tune is bad. It's going to be really hard to get your FT's right without a logger. If I had to guess, I would say that your rear O2 is shot and needs to be replaced. I would also guess that the front sensor is ok, but your tune needs to be adjusted. <- That is my best advice based on what you have told me, but since I can't see the car in person and you don't have a logger, it's hard to say for sure.

I highly suggest that you take back the OBD-II scanner and pick up a logger. It will save you a ton of time and get your car back on track to running properly.

If I go into "sensor check" on the SAFC-I it shows 3 sensors (In-1 and In-2) which i'm guessing is the 2 o2 sensors by the voltage they give off, and the (Thrt) TPS.

I know for a fact that i'm running very rich just by my gas milage.. ( about 11.7 MPG )

Any advice for SAFC-I settings with my setup? I updated my mod list in my profile

My settings now are:
Low settings:
1k -10%
2k -15%
3k -18%
4k -18%
4.5k -18%
5k -18%
6k -18%
7k -18%
High settings:
1k -23%
2k -26%
3k -28%
4k -35%
4.5k -34%
5k -37%
6k -38%
7k -38%

Throttle points are:
Low 35% and High 85%


ANY help would be GREATLY appretiated!

Thanks for all the help so far!
-Frank

 

[DSM-Franek]

I am tuned with a SAFC 1, could that PO136 be from a dead o2 sensor?

I am seeing between .010 and .015 on my SAFC from the rear o2. At WOT at low RPMs and I see above 1v from the front o2 sensor on my SAFC.

-Frank

Ok, I don't know what I was looking at when I said i see above 1v from my front o2 sensor, maybe I got the decimal mixed up but, My front o2 sensor PEAKS at .105v at WOT from about 2.5K RPM on and is .015v - .020v at idle.

I'm definitley leaning towards this PO170 coming from my front o2 sensor now, and the idea the both my o2 sensors are SHOT .

What do you think?

Thanks!
-Frank