O2 sensor codes?

[GabrielPantoja1997_4.0]

Hey guys, I need some help. I've got a 1997 4 liter ranger with 4x4, and I've got a ton of o2 codes as well as some rich codes and a flashing airbag light. My codes are: p0135, p0141, p0155, p1132, p1152. And the flashing airbag light. I can smell the car running rich and it doesn't run great. It rocks a little at idle and gets pretty bad mpg. I've checked the o2 and all other fuses and also replaced all 3 o2s and nothing has changed. Help!

 

[franklin2]

You need to figure out why it's getting too much fuel. I have heard of problems with the fuel regulator on some of these trucks. I was searching for a picture of it, but the problem is your year is in a series where they changed the configuration of the regulator and it's hard to find a correct picture. If you do find it see if it has a vacuum line on it. Pull the vacuum line and see if it has fuel in the vacuum line. If it does, it's bad.

 

[Bronc3]

One thing you can easily check that I have seen cause this is for a ruptured diaphragm in the fuel pressure regulator. Find the regulator and pull the vacuum hose off of it. If there is fuel in the hose you have a problem. If this is the case you can cycle the key and fuel will sometimes shoot out of the vacuum port on the regulator too. This isn't uncommon and takes seconds to check without tools.

 

[Broosedamoose]

You may have a couple injectors hanging open also.

 

[GabrielPantoja1997_4.0]

Okay I'm going to check the fuel pressure regulator this afternoon when I'm off work. Would the diaphragm being ruptured also cause the o2 heater circuit codes I'm seeing?

 

[adsm08]

Okay I'm going to check the fuel pressure regulator this afternoon when I'm off work. Would the diaphragm being ruptured also cause the o2 heater circuit codes I'm seeing?

No, but excess fuel in the exhaust could.

 

[franklin2]

Okay I'm going to check the fuel pressure regulator this afternoon when I'm off work. Would the diaphragm being ruptured also cause the o2 heater circuit codes I'm seeing?

Don't know about the rangers, but I do know my Tahoe will set a "O2 heater code" but it's just a generic code, the computer really does not monitor the heater circuit. It may be the same for your ranger.

 

[GabrielPantoja1997_4.0]

Alright, just checked the vacuum line and it had no fuel in it. Any other suggestions? Another thing my truck has done since I got it that may or may not be related is whenever its cold out (40f) the truck will start and die right away unless I give it gas and hold 2k rpm for a few mins. And the mpg is horrible, probably sub 10mpg. I've looked at all the vacuum lines I can see from the top as well and don't see or hear any crazy vacuum leaks. My minds going to pcm ground problem? I don't really know how to test for that though

 

[franklin2]

Peck on the mass air sensor. You could clean it also. Also check the condition of the engine temperature sensor. What are you pulling codes with? It doesn't give you any data like engine temp does it? If the computer thought the engine was cold all the time, it would throw extra fuel to the engine. The mass air sensor also has a lot to do with how the engine is fueled.

 

[GabrielPantoja1997_4.0]

I cleaned the MAF a while back thinking that might be the issues, it was squeaky clean before I cleaned it but cleaned it anyways. The temp on my instrument cluster fluctuates normally when driving so I think that rules out the temp sensor. I'm stumped. I'm using a regular obd- 2 sensor that's unable to see live data and unfortunately don't have access to one that can right now. Any other suggestions? I don't know where else to look atm

 

[franklin2]

I just did a quick look at the diagrams for a 1997 ranger, seems they still used a separate single wire temp sensor just for the cluster gauge, and still use a separate two wire temp sensor for the computer.

Maybe you can do a search and find the proper ohm readings for that sensor at a certain temperature. Since your cooling system is working, it probably runs around 190-200F fully warmed up, I would be curious what ohms the sensor reads with the engine fully warmed up compared to what the manual says. Maybe someone on here has that info.

 

[GabrielPantoja1997_4.0]

Alright so I just did a little bit of reading on the subject, so are you thinking that the 2 wire temperature gauge could be sending the computer the wrong data, making the computer think the engine is cold? Interesting, when I get home I'll run a resistance test and get back to you

 

[Orca]

[...] I've got a ton of o2 codes as well as some rich codes and a flashing airbag light. My codes are: p0135, p0141, p0155, p1132, p1152.

Welcome to the forums!

Not being able to read live data from your scantool is potentially hurting your ability to diagnose, but let's give it a try anyway...

Assuming that I'm understanding correctly that you're still seeing those same 5 codes, then you should probably focus initially on dealing with the oxygen sensor problems since all 5 codes are related to O2 sensors. Ignoring the last 2 codes (which are Ford-specific) for the moment:

• P0135 = O2 Sensor Heater Circuit (Bank 1 Sensor 1)
• P0141 = O2 Sensor Heater Circuit (Bank 1 Sensor 2)
• P0155 = O2 Sensor Heater Circuit (Bank 2 Sensor 1)

These are reports of circuit-related problems, not necessarily sensor-related problems. It strikes me as odd that it would happen to all 3 sensors simultaneously. I know you said that you checked the O2 and other fuses, but if your 1997 is like my 2004 Ranger, then all the heated O2 sensors share a single fuse and that seems like it might explain all 3 codes appearing together, so I'd carefully double-check the O2 sensors' fuse.

If it's not a fuse problem, then are you sure that the new O2 sensors are of the proper type and are properly connected?

Next, I'd check if there are any problems with the wiring between the O2 sensors and the PCM.

Also, do you still have the old O2 sensors?

A search for code P0135 turns up this page, which has some good information (which would apply to P0141 and P0155 as well):

https://www.yourmechanic.com/article/p0135-obd-ii-trouble-code-o2-sensor-heater-circuit-malfunction-bank-1-sensor-1-by-jay-safford

BTW, the other 2 (Ford-specific) codes (P1132 and P1152) are triggered because inadequate "switching" (voltage swings) are being detected on the 2 upstream O2 sensors. But until you find out why those first 3 codes are happening, I wouldn't worry about these last 2.

Hope that helps just a bit. Please keep us posted on your progress and/or problems. Good luck!

 

[GabrielPantoja1997_4.0]

I appreciate everybody's advice and help a lot! Alright so just got done rechecking everything. Fuse is non blown and lights up a test light with key in run. Went down to b1s1 o2 and checked volts with key on, sitting at 12 volts to the sensor. Checked the resistance of the heater inside the o2 sensor and it read 6.2, which I believe is right around where it should be. The sensors I replaced the old ones with are Denso part # 234-4070 o2 sensors. I just pulled the pcm connector to check for bent pins or corrosion but everything looks good, grabbed some electric cleaner and cleaned it anyways. Don't know what else to check

 

[Orca]

[...] Fuse is non blown and lights up a test light with key in run. Went down to b1s1 o2 and checked volts with key on, sitting at 12 volts to the sensor. Checked the resistance of the heater inside the o2 sensor and it read 6.2, which I believe is right around where it should be. The sensors I replaced the old ones with are Denso part # 234-4070 o2 sensors. I just pulled the pcm connector to check for bent pins or corrosion but everything looks good, grabbed some electric cleaner and cleaned it anyways. Don't know what else to check

This is puzzling. You've clearly been thorough in your testing, and I'm a bit stumped here.

My source says that heater resistance should be "between 3 and 30 ohms", so it sounds like that's not an issue.

I've taken a look at the 1997 Ranger O2 sensor testing procedures and, paraphrasing a bit here, it says that "input is required from the ECT, IAT, MAF, and CKP sensors to activate the HO2S/O2S Monitor". I could be wrong, but I would not expect codes to be set for the O2 circuit if conditions were not appropriate for running the test(s). But it probably makes sense to be sure that all of those sensors are working correctly. Did you already validate the ECT sensor somehow, as @franklin2 had wisely suggested?

BTW, is the CEL (Check Engine Light) on now? Has it been on all this time?

IMHO, you're getting close to the point where, other than ringing the wires between the PCM and the O2 sensors, you really need a better scantool to diagnose this with any confidence. For example, if it were me, I'd carefully examine (and record) the freeze-frame ("Mode $02") data then do a "reset" of the codes, and then run the vehicle for at least 2 drive cycles (so that the O2 sensor codes have a chance to "set" again), and see what codes re-appear.

Also, analysis of "Mode $06" output would be quite interesting because it typically contains more details about heated O2 sensor testing, but you need a proper scantool (hardware and/or software) to read that. This is not necessarily expensive, but the typical inexpensive "Harbor Freight" scantool is not going to help.

I wish I had better advice to offer, but that's all I can think of for now.