Engine Code Help

[Troubleshooter]

Hey

OK. So I get the check engine light on and run the diagnostic using a code tool from the local auto parts store. It kicks out 5 codes.

Codes are as follows:

P0128: Coolant Thermostat. Checked engine temp and its running about 175-180 (the needle is not straight up). I am assuming its a bad thermostat and I guess I will have to replace it. Saw some posts on how to and will follow those. If anyone knows one without removing the alternator I would love that technique.

B0035 and B0040: Left and Right (respectively) front wheel speed sensor. This appears to be a very easy replacement. On youtube it shows how to on another car but principle looks the same. Take off wheel, pull out sensor plug from behind rotor, unplug cable, and replace. Sound right?



B0455 Steering Wheel Angle Sensor??

U1026 Loss of Class 2 Communication with Automatic Traction Control????

The above last 2 codes have me stumped. Any suggestions?

The other thought is why would all these codes, most unrelated (at least I think) all of a sudden pop up at one time. Something seems fishy. Any thoughts or suggestions are welcome.

Thanks

 

[gmcman]

You can change the thermostat without removing the alternator with a long extension. However the time saved from removing the alternator is almost negated by a slower process with it in along with possibly some swear words. Some have done it, but with it out you can change the temp sensor. Granted it may not be bad but this way you don't need to go back in there again for awhile.

The lower bolt of the alternator is a small pain but not that bad, break it lose then a short ratcheting wrench is your friend. I didn't completely remove mine but was able to swing it out of the way. If you change the sensor, a dedicated socket will make life easy or just dremel a slot in a 18MM deepwell.

Check for any crud in the ABS sensor tone ring, the "teeth" diretly under the sensor. Possibly unhook the sensor and check for corrosion. I would only speculate the last 2 codes are from the ECM not knowing the relation of all 4 wheels but that's a guess.

 

[The_Roadie]

The steering wheel angle sensor is a common failure item. The SS-specialty site tbssowners.com has a nice write-up in their how-to section: I bought a steering angle sensor..... - TBSSOWNERS.com Forums

 

[Troubleshooter]

Thanks to both of you. Much appreciated.

Roadie, Im pretty handy but the extent of handy on this is yet to be determined. Is the Angle sensor something to be tackled as a DIY or better left for a mechanic?

Thanks

 

[Chickenhawk]

The coolant temp code was addressed by the above folks, and will be fixed by changing your thermostat (and perhaps your coolant temp sensor as well.)

The steering wheel angle sensor is not an emissions code; it is tied in to the ABS/electronic stability control systems, and thus codes are stored in memory. When that code first comes up, it should light your service stability control light. 99% of the time, that light goes out at the next restart.

So, the important thing to ask is if your service stability control light is on constantly now or did it come on a time or two and go out at the next restart?

If the service light stays on or comes on more than once or twice every few months, then you will need to replace your steering wheel angle sensor.

If the service stability control system light is currently out, and only came on once or twice, then it is simply the steering wheel angle sensor getting a bit of corrosion on the inside. It is a bit like a variable rheostat that spends 99.9% of its life in the straight ahead position. The sensor needs to make clean physical contact and sometimes the outer edges don't get used enough to keep them "polished" so to speak. (It is much more sophisticated than what I describe, but you get the idea.)

Usually what happens is you park the vehicle for a day or two with the steering wheel at a bit of an angle; the sensor doesn't make good contact with the lesser-used area of the sensor and it lights the service light at the next start.

This is why driving a block or two and then restarting will get it back to normal.

As I said, if it has only happened a few times, I wouldn't worry about it. Unlike emissions codes that go away when the problem doesn't return after a certain amount of cycles, stability control codes stay in history until erased.

Your first priority is the thermostat/coolant temp sensor (I would also get your exhaust backpressure tested to see if it harmed your cat converter) and your wheel speed sensors. Good luck and let us know how it goes.

Was the vehicle sitting without being driven for a few weeks by any chance?

 

[Troubleshooter]

omThanks. The car is driven every day pretty much. The light came on and by chance that same day I needed to disconnect the battery for an unrelated reason. The Engine light went of for a day and then came back on and has stayed on.

No other lights come on other then the generic engine light by the way.

I will do the thermostat and temp sensor ASAP.

I'm worried about whats involved with changing the steering wheel angle sensor. I hope that is a DIY project as well. From Roadies link, this is the description: Im not sure how to disable the SIR and how to disconnect steering column/intermediate shaft.

Removal Procedure

1.Disable the SIR system. Refer to SIR Disabling and Enabling . Notice: The wheels of the vehicle must be straight ahead and the steering column in the LOCK position before disconnecting the steering column or intermediate shaft from the steering gear. Failure to do so will cause the SIR coil assembly to become uncentered, which may cause damage to the coil assembly.
2.Position the front wheels straight ahead and lock the steering column to prevent rotation of the steering wheel.
3.Remove the intermediate shaft from the steering column. Refer to Upper Intermediate Steering Shaft Replacement (See: Steering\Steering Column\Service and Repair\Upper Intermediate Steering Shaft Replacement) .
4.Remove the steering wheel position sensor retainer screws (1).
5.Remove the steering wheel position sensor retainer (2) from the base of the steering column.
6.Disconnect the electrical connector from the steering wheel position sensor.
7.Remove the steering wheel position sensor (3) from the steering column.


Installation Procedure


1.Position the steering wheel sensor (3) to the steering column.
2.Position the steering wheel sensor retainer plate (2) to the steering column. Notice: Refer to Fastener Notice .
3.Install the steering wheel position sensor retainer screws (1). Tighten the screws to 10 N.m (89 lb in).
4.Remove the steering wheel position sensor anti-rotation pin from the sensor.
5.Connect the electrical connector to the steering wheel position sensor.
6.Install the intermediate shaft to the steering column. Refer to Upper Intermediate Steering Shaft Replacement (See: Steering\Steering Column\Service and Repair\Upper Intermediate Steering Shaft Replacement) .
7.Enable the SIR system. Refer to SIR Disabling and Enabling

 

[The_Roadie]

Start here: http://gmtnation.com/f23/need-manuals-get-them-here-371/

 

[Chickenhawk]

If it was me, I would ignore the steering wheel position sensor for now.

Watch for the "SERVICE STABILTRAK" light and if it ever comes on, let us know how often. Also note any conditions, such as was it parked for more than a few days and was the steering wheel straight or turned while parked.

The stabiltrak light is different from the check engine light. The "SERVICE STABILTRAK" light looks like a pictogram of a vehicle with skid marks and a wrench beside it. If it rarely comes on, don't worry about it. Just note how often and let us know.

Also, remember that if that "SERVICE STABILTRAK" light comes on even once, it will store that code in memory forever until erased. If you say the only light you ever saw is the check engine light, then don't worry about the steering wheel position sensor. It may have come on only once since the day the vehicle left the factory, but it stays in the memory until erased. (Disconnecting the battery does NOT erase ABS/Stabiltrak codes.)

If the other Stabiltrak light comes on by itself - the "STABILTRAK INDICATOR" that shows a pictogram of a vehicle with the skid marks, surrounded by a triangle symbol - then it is just telling you the system is working normally and the tires detected slippage that kicked in the traction control.

So get your thermostat done and don't worry about the steering wheel position sensor for now. Keep us informed.

 

[Troubleshooter]

Well the very next day the check engine light turned off. No codes at all. I notice the temp needle back up to 210 (staright up). My guess is a bad temp sensor or the Thermostat is getting stuck now and then

This leads me to my original thought. So the thermostat became "unstuck" or the sensor now works again. Why would the steering angle sensor code and the ABS Wheel speed sensor codes go as well. Very screwy. They all came on at once and now they all go off at once.

The Thermostat and sensor are getting changed regardless. If it sticked once, it will most likely stick again.The others.....beats me.

 

[Chickenhawk]

Thermostats rarely "stick" and "unstick." They tend to stick more open in the long term. They manifest themselves as a consistently low coolant temperature. (This is why some folks have INSISTED their thermostats are fine; they have seen the needle a few ticks to the left the whole time they owned the vehicle. Sadly, even if it doesn't get bad enough to throw a code, it will burn lots of gas and will eventually roast their cat.)

On the other hand, fluctuating coolant temp readings - especially if they seem to come on fairly suddenly - are almost always the coolant temp sensor.

The reason we advise people to change them both is that there is no definitive way to tell which one it is, and they are side-by-side anyway. If you feel brave, change just the coolant temp sensor and that will solve that problem. If you are more pessimistic, change them both. (When my temps started fluctuating on the highway, I bought both parts but elected to only change the coolant temp sensor to see if my diagnostics were correct; they were. Plus, changing the sensor does not require draining any coolant. You will lose only a few drops.)

As for the wheel speed sensors, I can't help you. I just don't know that much about them.

The B0455 Steering Wheel Angle Sensor and U1026 Loss of Class 2 Communication with Automatic Traction Control stem from the same thing with the steering wheel angle sensor. It is very intermittent and, as i said, ignore it for now and see if it ever comes on again.

Frankly, I think all your sensor lights were either just coincidence, or your ignition switch is failing.