So my check engine light came on a few weeks ago, stayed on for a half day then went out, it recently came back on and has stayed on for 2 days. I went to autozone and used the reader. The code is "P1133" which was not defined in the reader itself, I had to go online and find out what the code meant- it says, "Oxygen sensor heater circuit malfunction (Low)"

Okay, so in layman's terms will someone tell me where this sensor is located, what it does, and how to test it? I know you can do a voltage check but I'm not sure what voltages to expect.

 

Last time I bought a O2 sensor was for my wifes Intrepid and it cost like 40$. I can't afford this this week so will I hurt the car if I keep driving it?

 

Any help is appreciated!

Hi. Ok first, need to know your soob year and model.

 

P1nnn and P2nnn are manufacturer and model specific.

How many miles on it?

 

This o2 sensor needs to be an OE sensor if its thr front sensor. If you dont smell any rich exhaust, notice a drop in gas mileage, or smell any sulfur your good for a while, but replace it when you can.

 

nipper

Hi. Ok first, need to know your soob year and model.

 

P1nnn and P2nnn are manufacturer and model specific.

 

yeah, sorry

 

2000 OBW 81k miles

How many miles on it?

 

This o2 sensor needs to be an OE sensor if its thr front sensor. If you dont smell any rich exhaust, notice a drop in gas mileage, or smell any sulfur your good for a while, but replace it when you can.

 

nipper

 

OE as in I need to purchase it at the dealer or will NAPA have what i need?

OE as in I need to purchase it at the dealer or will NAPA have what i need?

 

OE get it at an online dealer, its cheaper. The 2nd sesnor can be autozone.

 

 

nipper

[...]P1nnn and P2nnn are manufacturer and model specific.

Anyone needing specific code info might want to try this Innova/Equus page: http://www.iequus.com/support/obd2_definitions.php

 

Just make sure to look for the particular make.

[...]I can't afford this this week so will I hurt the car if I keep driving it?[...]

When the engine is started "cold", the ECU runs "open loop"; that is, the engine gets fed a predetermined rich fuel mixture. Once the oxygen sensor is hot enough, it provides a signal that allows the ECU to adjust the mixture (it runs "closed loop"). The exhaust stream can heat the oxygen sensor to operating temperature, but that typically takes a few minutes; in order to help minimize exhaust emissions, front oxygen sensors often incorporate an electrical heater to warm the sensor faster. If the heater isn't working correctly, your car will waste some gas and pollute more than it should for a few minutes after each cold start. Once the sensor gets hot due to the exhaust, operation should be normal, even if the heater isn't working.

 

So, it's unlikely that your car will be hurt due to this problem. At worst, besides the slight additional fuel usage, there might be a lttle bit of fuel dilution of the engine oil. Still, I'd suggest taking care of the problem when you can afford to.

can someone suggest a good online place to buy OE parts?

and also, I did a generic quick search for Subaru O2 sensors and it doesn't seem to be "front" or "rear" specific. Is this true? it's the same sensor just the front one has to be OE?

 

Oh and also, where is this thing located? In the exhaust path obviously but between the cat and exhaust manifold or someplace downstream?

can someone suggest a good online place to buy OE parts?

and also, I did a generic quick search for Subaru O2 sensors and it doesn't seem to be "front" or "rear" specific. Is this true? it's the same sensor just the front one has to be OE?

 

Oh and also, where is this thing located? In the exhaust path obviously but between the cat and exhaust manifold or someplace downstream?

 

http://www.genuinesubaruparts.com

http://www.1stsubaruparts.com

http://www.subaruparts4you.com

 

typically there are 2, one before the cat and one after. the front one, before the cat needs to be OEM, get it online . the rear one after the cat can come from any parts store. they are a little larger than a spark plug and thread into a fitting welded into the exhaust pipe with 3 or 4 wires (one connector) running to them.

[...]I did a generic quick search for Subaru O2 sensors and it doesn't seem to be "front" or "rear" specific. Is this true? it's the same sensor just the front one has to be OE?[...]

The P113x codes are usually for front O2 sensor problems. The P1133 code therefore probably indicates the front sensor (or wiring/connection) is where the problem is. If a new front sensor is needed, it's usually best to get an OEM one, since it's the one that's critical to how the ECU adjusts the air/fuel mixture.

 

EDIT: It seems P1133 doesn't necessarily indicate a heater problem restricted to the front sensor; see following posts in this thread.

I have seen a few posts for circa this model year for front o2 heater circuit malfunctions and it was some relay or something that needed to be replaced. It could be the heater in the sensor has opened or shorted or a wiring issue etc.

 

If you decide to replace the front o2 sensor, definitely go OEM on this one. It is a five wire sensor on a six wire connector. In other posts people have ordered the cheapest sensor they could find and the connector and wires were different....so it wouldn't work.

I have seen a few posts for circa this model year for front o2 heater circuit malfunctions and it was some relay or something that needed to be replaced. It could be the heater in the sensor has opened or shorted or a wiring issue etc.[...]

Porcupine73 has a good point; since the Subaru P1133 code doesn't indicate a particular sensor, it may well be a heater circuit problem but not at the sensor itself.

If you can get the troubleshooting procedure for this code that might be something to check out.

I just looked at the wiring diagrams for the '99 OB/Legacy and '01 Forester (I don't have the '00 OB/Legacy one handy), and the O2 sensor heaters (front and rear) are fed via a set of contacts in the main relay; it's therefore possible that it or related wiring/connections could cause a problem triggering the P1133 code.

Oh right on, 2000 Outback, I have one of those....checked the service manual, which says (for auto trans vehicles):

 

DTC P1133 - FRONT OXYGEN (A/F) SENSOR HEATER CIRCUIT HIGH INPUT

DTC DETECTING CONDITION: Two consecutive driving cycles with fault

 

Then it has a bunch of voltages and currents to measure and harnesses to shake. Most of them end in repairing a connection.

 

Oh right on, 2000 Outback, I have one of those....checked the service manual, which says (for auto trans vehicles):

 

DTC P1133 - FRONT OXYGEN (A/F) SENSOR HEATER CIRCUIT HIGH INPUT

DTC DETECTING CONDITION: Two consecutive driving cycles with fault

 

 

So in short, should I even bother w/ troubleshooting the circuit and comfirming the proper voltage outputs? Because according to what you're saying it all ends up at the connector which gets replaced w/ the sensor anyway.

 

 

HOWEVER, in the other post someone mentioned that the fault could be nearer to the relay itself, in which case the sensor harness would be okay.

 

Then it has a bunch of voltages and currents to measure and harnesses to shake. Most of them end in repairing a connection.

If a voltage check is in order I'd need to know what the pinouts are and what values to check for. Well I guess I'd just need the values, the pinout is illustrated in the attached image.

 

EDIT:

I just did a quick search for an OE sensor and I'm seeing prices between 140-170$ !!! Is that right!?! Good God!

Yes, the OEM oxygen sensors aren't cheap; but you know you'll get something that will work.

 

Anyway, the procedure has a bunch of voltage and current checks, and says a few times to 'repair short in harness' (sorry if I mislead by saying connector). I didn't see off hand any branches ending in 'replace o2 sensor'.

Yes, the OEM oxygen sensors aren't cheap; but you know you'll get something that will work.

 

Anyway, the procedure has a bunch of voltage and current checks, and says a few times to 'repair short in harness' (sorry if I mislead by saying connector). I didn't see off hand any branches ending in 'replace o2 sensor'.

 

Any way you can share that procedure w/ me w/o too much trouble?

I have more electronics skills than I have money at this point, so if I can fix the harness by repairing a connector somewhere then I'll do it. At least for now.

 

Thanks

By the way, there was a recall for bad O2 sensors on certain 2000 model year Subarus. It wasn't specifically for heater trouble, but it might be worthwhile contacting a dealer or SoA and see what they'll do (at no charge ).

Yes, my '00obw had the front o2 sensor replaced under that recall. It was something about the tip of the o2 sensor could break off and get lodged in the cat or something.

 

I was looking at the troubleshooting procedure on alldatadiy.com. It's a web page with a bunch of diagrams and text and such.

Check engine light on and off all the time. Have performed all recommended maintenance. Had O2 sensor replaced, it was faulty, dealer put in another. Now stuck with same problem. On and off, on and off. I am so tired of this! Go to auto repair shops and they say possibly need new gas cap, fuel injector, O2 censor, knock sensor, possible vapor leak, catalytic converter. My car has 132,000 miles so I can't get emissions stuff done under warranty. What the hell is going on with check engine lights in Foresters? I can't get my vehicle inspection approved with the check engine light on. I have MS & support a family so like most of us don't have tons of money to spend on a car I have taken very good care of. Can the dealer reset the light long enough for me to get an inspection sticker until I have enough money for repairs? And how do I know for sure exactly what repairs are necessary or not? I'm no mechanic, I'm a nurse. Don't want to rip anybody off, but don't want to get ripped off either. Should have studied auto mechanics instead!

Well first thing you need to do is get to an autozone and tell us exaclty WHAT the codes are.

 

When you say the CEL is on and off, is it flashing, or coming on steady then going off.

 

We will start over from scrtach.

 

Did you have the timing belt replaced at 105,000 miles?

 

When was the last time it had a tune up?

 

nipper

edit: moved my reply to lorimansell here -> http://www.ultimatesubaru.org/forum/showthread.php?p=669220