How to fix code P057 on 95 cadillac concours 4.6 ltr engine

[wcrowe]

Hello Forum,

When I put my car in drive, I hear a knocking noise, however, as I drive, I don't hear it anymore!. It's only after starting my car do I hear the noise. I pulled the codes and P057 came up. I checked transaxle fluid with car on level ground and the readings were fine. The car drives fine. It's only when I start it, put in it in drive and move forward do I hear this knocking sound. What could be wrong and is there anything I can do before I take it in for a check up? It just turned over 116,000 mi.

Thank you,

W. Crowe-Owner

[Cadillac Jim]

P057 (E057) Shorted 4th Gear Switch Circuit Or Shorted 3-4 Shift Solenoid

This probably means that there is a problem with the big wiring harness connector to the transmission, or one of the wires is damaged. You should be able to inspect it from under the car.

Check the motor supports. In particular, look at the "dog bones," the large aluminum struts between the engine and the top radiator support. If these are bad, the rear of the motor could be knocking on the firewall when you shift the transmission. It wouldn't hurt to look at the motor supports on the bottom, too.

[wcrowe]

Thank you Cadillac Jim for your knowledge and expertise,

I purchased both " dog bone supports" and installed them on front of motor, however, still getting knocking noise. I inspected underneath vehicle and heard the knocking sound. The vibration is causing my muffler to knock as well. Where underneath are the motor supports and can these be tightened?

Thanks

[Cadillac Jim]

There are two underside motor supports, a front motor support and a transmission support. The rear (transmission support rarely goes but with a 19-year-old car it is possible. The front motor support will go quickly if the dog bones are loose. With good, tight dog bones, though, it's hard to tell when the front motor support is bad.

The fact that the exhaust is rattling is a big red flag that the motor supports *are* the problem. The lower motor supports are rubber and metal, all vulcanized into a single assembly, and the bolts are to metal, unlike the dog bones that bolt through rubber (neoprene) bushings. You might make sure that the dog bones are really tight enough, though. The torque for the dog bones' mounting bolts is pretty stiff.

[wcrowe]

Thank you Cadillac Jim and all the other experts on this site for your knowledge, expertise and mostly your time. I greatly appreciate you andThank you.

Just went in for emissions and failed. Reason car failed emissons was high NOx. State official from Colorado stated I need to fix P057 code, (which has been ongoing), need new catalytic converter, which he stated the substrate was producing the rattling noise that i was hearing, and that the vehicle was misfiring. I have a Concours 4.6L vin# Y. No other codes are showing after clearing PCM. Had spark plugs replaced, ordered new CAT. Machanic friend stated that it would be good idea to do a three month cycle of Royal Purple fuel/injector cleaner before investing in new fuel injectors. Did inspect wires (the ones I saw underneath car) for damage. Nothing obvious stood out. P057 has to do with automatic transmisson shift sensor 3-4 which I have no clue where it's located! Is it within Transmission housing somewhere? If so, I assume I have to take it into shop.

Cadillac Jim, what steps do you recommend I follow to pass emissions? The MAP sensor I have on my car looks like the MAP for a base model and not Concours. It has the two screws on both sides with vacuum portal/hose connection to brake booster.

Thank you, Wythe, 1995 Cadillac Concours 4.6L engine

[Cadillac Jim]

The 3-4 shift solenoid is one of three inside the transmission. They are changed with the transmission in the car but it is not an easy DIY job. The transmission is drained, then its oil pan removed, than a cover plate. Several "ball bearing" valves are exposed and you must keep the balls and put them back exactly where they belong when you put everything back or the transmission won't work properly. There are others that will help you there.

If you run 91 octane or higher gas, you probably don't need your injectors cleaned. If you do, Techroline is the only gas additive that GM recommends for Northstars, and it will clean your injectors.

A bad oxygen sensor or a wire off the sensor can throw a P0057, an OBD II code. I've heard it from Logan, KHE and others that the 1995 model year has a few OBD II codes.

The knocking at low speed in-gear could also be a CV joint.

I'm good at diagnosing things from codes but we need 1995 model year experience here. Also, we need hands-on mechanic experience; my 1997 ETC gave very little trouble, ever.

[barczy01]

Does the car shift ok? On alldata a p057 is a shorted transaxle temp sensor circuit.

[Cadillac Jim]

Yes, a cracked cat element usually produces a rattle at idle or just above idle. If it's the cat, replace it before the ceramic element starts shedding pieces into the mufflers and ruins them.

I'm beginning to think that this is a P0057, an OBD II code from the 1995 GM repertoire.

[wcrowe]

Thanks again Cadillac Jim.

I'm replacing the CAT on 08/24/2015 so I should know something after that. Model Concours, year is 1995. The car shifts nice and smooth so no issue there. Ran codes this morning and T031 and T035 came up. What do those mean? That P057 shows consistently. Like Cadillac Jim stated, we'll see what happens after CAT is replaced.

[Cadillac Jim]

T031 RR Wheel Speed Sensor Fault
T035 LR Wheel Speed Sensor Fault
P057 (E057) Shorted 4th Gear Switch Circuit Or Shorted 3-4 Shift Solenoid
P0057 Heated Oxygen Sensor (HO2S) Heater Circuit Low Voltage Bank 2 Sensor 2

First, check the connectors to the rear wheel speed sensors. They are at the center of the hub on the inside. If they are good, follow the wheel speed senor wire from either rear wheel and look for a wiring harness problem at or after the point where they come together in the wiring harness.

If the transmission never showed a driveability problem, make sure that the last code has one zero in it. If it has two zeros, the oxygen sensor on the back of the CAT has a wire off the heater, the harness has a problem with that wire elsewhere (it runs between the engine and the firewall), or the oxygen sensor is bad. This could have been bad with no problem with your CAT; P0057 is an oxygen sensor code, not a CAT code. It this has been a transmission code all this time, your transmission has been running in a fallback mode, with rough shifts, no memory of driving habits, etc.

[wcrowe]

Hi Forum,

Happy to report that my 1995 Cadillac Concours passed emissions. Took it to garage shop I found and they did good job diagnosing issue. Problem was bad ignition coil that was causing misfire. Replaced it and everything is all good for the exception of P057. I took it to transmission guys here in Denver, Co and they noticed burnt smell of fluid which I'm sure shorted the sensor. They stated that the tranny is on borrowed time and to baby it. I'm second owner and never had fluid changed. Only has 136,000 miles! It shifts perfect. Only problem is sensor is inside tranny which is major job to get to and very costly. Any suggestions?

Thanks,

wythe

[winterset]

I am leary of someone judging the condition of a 4t80e without tearing it apart. Did you have clutch material in your pan? How old is the fluid possibly 21 years? Do you know if it was ever changed? Old fluid would smell really bad and scarry.

If it is a shift solenoid, that can be done by just dropping the pan. With the exception of the torque converter issue which you DO NOT have a code for, the consensus is that these transmissions for the most part are bullet proof. I would get a 2nd opinion on the transmission. Drop the pan, change the fluid with only the new gm approved dexron vi, check out the 3-4 shift solenoid, and replace if suspect.

There is a way by disconnecting the trans cooler line at the radiator where you will get most of the fluid out (disconnect, attach a hose to a bucket, start it up in park, and as soon as the fluid stops pumping, shut it off. Never put it in gear while doing this method) or when the pan is off, you can open the torque converter drain plug which i believe is INSIDE the transmission case. I recall You should get out like 12 quarts.

[Cadillac Jim]

I would smell the transmission dipstick myself. Comparing the smell to that of a known good transmission dipstick of similar vintage is a good idea.