P0642 code comes up when coasting
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krissondors
- LE Member
- Posts: 3
- Joined: Sun Mar 30, 2014 4:35 pm
- Year and Trim: 1995 SSEi
P0642 code comes up when coasting
Hi everyone, new to the place. I recently bought a 95 ssei and I love it. Needs some tlc but its nice. So I have my ses light come on and the car drives great BUT I am only getting about 2# of boost. I bought it off my friend and before the light came on it was hitting around 7#. Anyway, the code is p0642 which is quad module 1. Im 90% sure its the tcc circuit because the code only comes on when coasting. I replaced all four solenoids and still no luck. I have alldata and on demand and I did all the tests I could without the tech 2. Any ideas what I can be? Thanks!
- J Wikoff
- Administrator

- Posts: 17080
- Joined: Mon May 19, 2008 7:01 pm
- Year and Trim: 1992 SSE
2009 G8 GT - Location: Central Illinois
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Re: P0642 code comes up when coasting
Is that similar behavior to a bad egr?

WHITE WHINE - 1992 SSE Supercharged 236.26 ci (.040 Over) 15.090 at 90.2 MPH on old engine w/ slipping trans & melted O2 sensor - Gen 3 M62 and matching TB, Gen 2 Pully, Zillamotorsports Ported LIM, YT 1.72 Roller Rockers, SII FPR & Injectors, Hypertech Thermomaster chip w/ 160 Thermo, TransGo Shift Kit, Infinity/Pioneer Speakers & a 10" Alpine Type R Sub, all the watts, 140 amp Alternator, Ricepipe CAI w/ heatshield, Pilot Angel Eye Foglights, Clear Corners, '02 17" Chrome Bent 5's, Magnaflow F-Body Muffler and Hi-flo Cat, Ceramic Coated Ported Exhaust Manifolds, Fan Override, Monroe Reflex struts, red calipers
2009 G8 GT - Sport Red Metallic, loaded, SOLO Axlebacks, Rotofab Intake, Tuned, autodim mirror, removed intake manifold cover, HSV GTS triple gauge pod, two tone red-hot shifter and HSV SuperSport steering wheel, GXP rear sway bar and diffuser, 3.45 diff and various Camaro suspension bits, LED Taillights
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krissondors
- LE Member
- Posts: 3
- Joined: Sun Mar 30, 2014 4:35 pm
- Year and Trim: 1995 SSEi
Re: P0642 code comes up when coasting
As far as I understand, EGR has nothing to do with itJ Wikoff wrote:Is that similar behavior to a bad egr?
Re: P0642 code comes up when coasting
try another PCM. 94 & 95 are notorious for pcm's going bad.
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krissondors
- LE Member
- Posts: 3
- Joined: Sun Mar 30, 2014 4:35 pm
- Year and Trim: 1995 SSEi
Re: P0642 code comes up when coasting
That's what my suspension is. If I had one handy I'd do it but seems like a expensive test. Im going to purchase a tech 2 at some point so if I dont find the problem by the problem by then hopefully ill figure it outPopaTim wrote:try another PCM. 94 & 95 are notorious for pcm's going bad.


