95 blazer Engine check light

Ive got a 95 blazer with 171,000km on it, and the check engine light has come on about 3 times in the past few days. The last time it came on, it stayed on and still is on, yet the engine sounds practically no different, its quite confusing. I'm wondering if anyone out there is either havin the same issues or had them, or just may know what i can do about this. My only thought would be an oxygen sensor possibly but im totally stumped. Any ideas or tips would be greatly appreciated.

- Jesse

Time to get the engine codes checked.... No sense guessing at what the SES light means when you can go to Auto Zone and have it checked for free....

My guess is:

-- O2 sensor (The one behind the Cat went out on mine)
-- EGR Valve (This is a very fussy engine with respects to the EGR)

....but let us know what you discover. BTW, was there a change in your gas mileage or performance?

Ive got a 95 blazer with 171,000km on it, and the check engine light has come on about 3 times in the past few days. The last time it came on, it stayed on and still is on, yet the engine sounds practically no different, its quite confusing. I'm wondering if anyone out there is either havin the same issues or had them, or just may know what i can do about this. My only thought would be an oxygen sensor possibly but im totally stumped. Any ideas or tips would be greatly appreciated.

- Jesse

Get the codes scanned and find out what codes come up.

Don't do anything until you know them.

In response to wether my mileage or performance decreased or changed in n e way...... Im not too sure, nothing hugely noticable if there was, cause like i said befre, the engine is practically normal, the way it was before the light came on..... Anyways, in respects to fuel efficiency, they arent very fuel efficient these vortecs, haha, bottomless belly if u ask me.

On a similar note however, bein not so knowledgeable of cars to begin with, im always wonderin what is maybe a cheap or simple way to gain some extra horsepower out of my blazer. Just lookin for maybe some simple tips or somethin to boost her a little if i can. The blazer i haev is a 1995 Blazer LT 4 Door 4x4

Anyways, anything helps, thanks for the help guys I more than appreciate it!

- Jesse

Let's focus on the engine problem first and move on from there.

I live in Vancouver, BC, CANADA. So as for goin to auto zone and finding out the codes thats somethin i cant do, but what i do plan on doin is goin down to the GM dealership and seein what they say.

I live in Vancouver, BC, CANADA. So as for goin to auto zone and finding out the codes thats somethin i cant do, but what i do plan on doin is goin down to the GM dealership and seein what they say.

Or go to a shop with a snap on scanner and have them do it.

Just don't pay too much.

Should only cost about 30-40 to have the ECM scanned and while you are at it, you might as well have them update you computer firmware with the latest fixes.

I live in Vancouver, BC, CANADA. So as for goin to auto zone and finding out the codes thats somethin i cant do, but what i do plan on doin is goin down to the GM dealership and seein what they say.

Unless you have no other choice, I'd stay away from the Dealership unless you really want to spend some big bucks. I'm sure in a city as big as Vancouver, you should be able to find a reputable garage to read the codes for you. If you can get the codes, write them down and post them back here on this Forum and see if we can help you. :smile:

Unless you have no other choice, I'd stay away from the Dealership unless you really want to spend some big bucks. I'm sure in a city as big as Vancouver, you should be able to find a reputable garage to read the codes for you. If you can get the codes, write them down and post them back here on this Forum and see if we can help you. :smile:

Canada doesn't have the huge price giuging like they do in the states.

Mine cost $40 CDN and they also updated the software for me.

Canada doesn't have the huge price giuging like they do in the states.

Mine cost $40 CDN and they also updated the software for me.

Wow! Too bad I live 2000 miles away from the Canadian border. Local dealerships will usually want to charge you a scope fee of Approx. $60.00 - $80.00 USD to even look at your truck. :banghead:

Hey, Ive checked into gettin the codes read and its crazy, the price difference all over the place, canadain tire $120 dealership $99 my local garage $45!! So im gettin the codes read monday, and then we'll see from there. In the meantime, Ive continued to drive it, with it still sounding no diff, totally normal, so i assume its just a dead or malfunctioning sensor. Anyways, we'll see and when i do get them read ill be sure to post up the codes for ya to check out, and let u know the final outcome.


- Jesse

Hey, Ive checked into gettin the codes read and its crazy, the price difference all over the place, canadain tire $120 dealership $99 my local garage $45!! So im gettin the codes read monday, and then we'll see from there. In the meantime, Ive continued to drive it, with it still sounding no diff, totally normal, so i assume its just a dead or malfunctioning sensor. Anyways, we'll see and when i do get them read ill be sure to post up the codes for ya to check out, and let u know the final outcome.


- Jesse

Get the dealer to do it and have them update your computer software.

Worth the money.

Yeah, the reason im not goin to bother with goin to the dealer is because they quoted me that to get the codes checked is 99$ and then to update the software is ANOTHER 99$. That puts me in bout 200 plus dollars. So right now im just gettin fixed what needs to be and then ill take it from there....

- Jesse

My Chev dealer upgraded the programming and checked the computer for CDN$83.

I would shop around a bit at another dealer.

So Ive finally got it into the shop and back again..... Had the codes read.

Turns out to be 5 codes, 4 relating to the front O2 sensor, one to the back O2 sensor. So I went ahead and got the upstream O2 sensor replaced with a new one from ACDelco, the check lights gone out and the garage has said the light may come back on, if it does, its probably to do with the O2 sensor behind the cat. Should the light come back on, Im entitled to return to the garage at no cost and have my codes read.

Anyways, problem solved. Incase someone was interested in the code numbers here they are:

P0133
P0134 ____ All of these relating to the
P0135 upstream O2 Sensor.
P0141

P1133 ____ This one relating to the O2
sensor behind the cat.


Aside from all this, thanks alot for your interest and tips everyone.

Your help and attention is greatly appreciated!


- Jesse

Make sure you completely reset the computer by pulling the negative erminal off of the battery and the two ECM fuses in the panel to allow the computer to reset and relearn the air/fuel mixture curve.

So Ive finally got it into the shop and back again..... Had the codes read.

Turns out to be 5 codes, 4 relating to the front O2 sensor, one to the back O2 sensor.
- Jesse

I am able to cause all my oxygen sensors to do the same thing. This is especially the case with with NEW O2 sensors. I just did mine. This usually happens when I am at a low RPM and then I try to accelerate too quickly, especially if the O2 sensors are new! This can cause the O2's voltage to go into OFFSPEC for voltages and then give me 'false' error codes. The computer then runs in open loop mode fuel mixture causing increased gas mileage and a hotter catalynic converter. I have seen this with all brands of O2 sensors. As the O2's get older (more sluggish - not good) this bogus O2 error stops happening.

If I couldn't afford the $60-90 bucks to get the codes read, or the $30 USD for a OBDII code scanner, I would just reset the computer (pulling the +ive battery terminal off for about 10 mins does this) to clear the codes, run the vehicle to see if a code comes up again. If the light doesn't come back on (chances are this is the case), then you're fine.

If I went to the dealer everytime "Spend Money Light" turns on, I would have spent about 1.5 thousand on O2 sensors and other 'bogus' errors. Since owning my car, I've had about 8 O2 lights (300 Cdn for dealer to swap out - $70 to scan + $98 Labour + $150.00 for the part), and 3 EGR lights (Guess about $300 each of these). All of them would have been expensive to get fixed.

Initially I ran with a cheap 'scan tool' that I bought from Cdn Tire (I paid $250Cdn about 8 years ago). You can pick em up 'cheap' on ebay etc ($30 USD). Highly recommended item. You can *OWN* your own scan tool for what it costs to get the codes read once at a shop or dealer once. Code reading is just another way in which people try to rip you off!

I would then take note of the codes, and if they come up again fairly quickly, then I would replace. With O2's this is not always the best way as they really should be swapped out at around 100,000 miles (for the 4 wire variety O2 in your car). The only real way to test and O2 is with an expensive car - computer interface ( about $400.00 cdn - I'm using Autotap).

Your car is at 170,000 KMs, so it is "about due" to get the engine O2's redone. I would keep the front two (left engine / right engine) O2 sensors in top condition. I suspect that the other 2 around the catalynic converter should be replaced with the 'used' Left Engine / Right Engine O2's if they are newer. The before/after catalynic O2's are used mostly for monitoring the pollution, and if they are 'sluggish' it's no big deal. If the two up near the engine are sluggish, then you'll get a bad fuel/air mixture!

I've owned a 1996 blazer for coming up on 10 years now.

Regards,
----- Robb ------

So Ive finally got it into the shop and back again..... Had the codes read.

Turns out to be 5 codes, 4 relating to the front O2 sensor, one to the back O2 sensor. So I went ahead and got the upstream O2 sensor replaced with a new one from ACDelco, the check lights gone out and the garage has said the light may come back on, if it does, its probably to do with the O2 sensor behind the cat. Should the light come back on, Im entitled to return to the garage at no cost and have my codes read.

Anyways, problem solved. Incase someone was interested in the code numbers here they are:

P0133
P0134 ____ All of these relating to the
P0135 upstream O2 Sensor.
P0141

P1133 ____ This one relating to the O2
sensor behind the cat.
Aside from all this, thanks alot for your interest and tips everyone.
Your help and attention is greatly appreciated!
- Jesse

Took a few secs to look up your code numbers for your 95 Blazer:
=================================================
P0133 = Slow Response Bank1 Sensor 1
P0134 = No activity Bank 1 Sensor 1
P0135 = Heater Malfunction Bank 1 Sensor 1
P0141 = Heater Probe Bank 1 Sensor 2 - Catalynic Converter
P1133 = System Insufficient Activity Bank 1 Sensor 1

Sounds almost like a loose wire to me?

Just FYI - Here's the freeze frame data from my 1996 Blazer's O2 failures. Notice that my error codes don't match the error codes on the 1995 version blazer.

When a 1996 or newer car sets an error code, it also logs quite a bit about what the engine was doing.

P0137 HO2S Circuit Low Voltage Bank 1 Sensor 2
>>Fuel System Status Bank 1 OL-1
>>Calculated Engine Load 73.3 %
>>Closed Loop Integrator Value 5 None
>>Desired Air Fuel Ratio 166 None
>>Injector PWM Average Bank 1 0.000 ms
>>Ignition Voltage 0.8 Volts
>>Engine Run Time 1,003,110 Seconds
>>Manifold Absolute Pressure (MAP) 28.1 in Hg
>>Engine Speed 4,648 RPM
>>Vehicle Speed 35 MPH
>>Mass Air Flow Rate 18.894 lb/min
P0131 HO2S Circuit Low Voltage Bank 1 Sensor 1
>>Fuel System Status Bank 1 OL-1
>>Calculated Engine Load 73.3 %
>>Closed Loop Integrator Value 5 None
>>Desired Air Fuel Ratio 166 None
>>Injector PWM Average Bank 1 0.000 ms
>>Ignition Voltage 0.8 Volts
>>Engine Run Time 1,003,110 Seconds
>>Manifold Absolute Pressure (MAP) 28.1 in Hg
>>Engine Speed 4,648 RPM
>>Vehicle Speed 35 MPH
>>Mass Air Flow Rate 18.894 lb/min


P0151 HO2S Circuit Low Voltage Bank 2 Sensor 1
>>Fuel System Status Bank 1 OL-1
----OL-1 means the engine went into Open Loop (rich mix) fuel.
>>Calculated Engine Load 73.3 %
----- Yeah I admitt it, I was really thromping on the engine!
>>Closed Loop Integrator Value 5 None
>>Desired Air Fuel Ratio 166 None
>>Injector PWM Average Bank 1 0.000 ms
>>Ignition Voltage 0.8 Volts
>>Engine Run Time 1,003,110 Seconds
>>Manifold Absolute Pressure (MAP) 28.1 in Hg
>>Engine Speed 4,648 RPM
------ Red line is at 5,200 RPM, getting close.
>>Vehicle Speed 35 MPH
------ I slowed to about 30 MPH and then GUNNED IT HARD!
>>Mass Air Flow Rate 18.894 lb/min

Pretty neat stuff, I thought. The O2 sensors were just replaced with brand new ones about 2 weeks previous, the're working fine. I've seen this issue with my 1996 with all brands of O2 sensors.

Regards,
---- Robb ----

No, it is a bad O2 sensor.

The one in front of the cat.

When it is changed, the rear O2 sensor code will no longer appear again seeing it is just there for CAT monitoring.

Hi Spblend : I had same problem on my 95 Lt blazer 4.3 L changing the o2 sensors is a great idea .... but more than likely whats causing them to fail is catalyic converter is plugging up causing them to carbon up . If not in vancouver where there is air care which I am not so before replacing my o2 sensors took my converter off . Runs better with new sensors now anything newer than 95 they say you can not take it off just won't run proper . Mine runs great noticed the mileage got better bit more power also stopped my egr valve from plugging up due to to much pressure from catalyic converter being plugged .