Check engine light, 99 Silhouette

ALLENMOB

MEMBER
1999 OLDSMOBILE

We purchased a used 1999 oldsmobile silhouette a few weeks ago, 132000 miles. (3.4 engine). 3 times I have received the check engine light on the instrument panel. Each of the times occurred after refueling a nearly empty tank (1/4 tank or less). The last time I tightened up the gas cap and the problem was solved but it has stayed on for the day this time. Also, right about the times that the light comes on the engine "hiccups', sometimes severely, and continues to do so until the light finally goes out. Any suggestions on what I need to check and/or how to fix and prevent this issue? Thanks!

6 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Get the vehicle to autozone and get it scanned for codes and comeback with it-this it the starting point for diagnosis.

Gas cap! Sounds like there's a problem with the evaporative system could be a purging solenoid/charcoal canister

OBD II also monitors the evaporative emissions (EVAP) system, but only once during a drive cycle. The purpose here is to detect leaks that allow fuel vapors to escape into the atmosphere. OBD II does this by applying vacuum or pressure to the fuel tank, vapor lines and charcoal canister. If OBD II detects no air flow when the EVAP canister purge valve is opened, or it detects a leakage rate that is greater than that which would pass through a hole 0.040 inches in diameter (0.020 inches for 2000 and up model year vehicles, which is the size of a pin prick), the EVAP system is malfunctioning and OBD II sets a code.

If you have a P0440 code indicating a fault in the EVAP system, finding the leak can be a challenge. The first place to start is the gas cap. A loose-fitting or damaged cap can allow enough air leakage to set a code. To find a vapor leak, you may need a leak detector that uses smoke and/or dye.

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Tuesday, October 30th, 2007 AT 12:27 AM

ALLENMOB

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Auto zone gave me an error code 742, about the transmission. 2 transmission places both gave me the same error code (+ a few more like a code for trying to start the car with an "uncoded" key). I'm going to take it to another mechanic and see what he says. They all say it's the transmission and the light/engine trouble coming on after a tank fill-up is nothing but a strange coincidence. Thanks.

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Thursday, November 1st, 2007 AT 4:36 AM

ALLENMOB

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P0742 TCC circuit stuck on

P1629 Fuel enable/incorrect no signal

P1811 Max adapt & long shift/ has to due with slippage of transmission.

The 3rd mechanic said that I have a celenoid? That needs replaced and the van should be fine. That sound right?

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Thursday, November 1st, 2007 AT 4:33 PM

RASMATAZ

MECHANIC
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The transmission is it shifting properly or delay in shifts?

The transmission operation has nothing to do with the evaporative system. That was your original problem- The last time I tightened up the gas cap and the problem was solved but it has stayed on for the day this time. I am assuming when it corrrected the problem it has to do with the Evap System not the tranny.

TCC " transmission converter clutch " solenoid could be the problem here or other shifting solenoids involved.

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Thursday, November 1st, 2007 AT 4:48 PM

ALLENMOB

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I've had the tcc and shift 1/2 (?) Solenoids replaced and the van shifts fine until it gets warmed up then it starts shifting hard. The mechanic said he didn't clear out the error codes from the computer and that is what is causing the problem to continue. The engine light hasn't come on since the parts were replaced. Is there anything else I should check? . Before or after the codes are cleared? . Will the computer clear out the codes itself or do I have to take it to have that done? Thanks!