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Old 03-21-2006, 09:00 PM   #1 (permalink)
joispoi
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Dtc P0238

Does anybody know the repair procedure for DTC P0238 Boost Pressure Sensor circuit High?

I'm picking up an new MAP sensor at Napa, tomorrow. Is there anything else to check? With engine off, the Baro and boost pressure sensor readings were the same at 101kpa.
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Old 03-21-2006, 09:13 PM   #2 (permalink)
gmctd
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Substitute a known good MAP, compare readings is the Goodwrench approved method, rite outa the service manual.

Difference is, Baro should read 4.91v, Map should read 2.31v at atmospheric pressure, give or take a few.

Other than that, try craniking the DIY boost spring backward a bit................
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Old 03-21-2006, 09:25 PM   #3 (permalink)
jac6695
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I was getting that code back in the summer. I never figured it out, and it hasn't come back in a while. Let us know if the MAP makes a difference.
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Old 03-22-2006, 11:46 AM   #4 (permalink)
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The only time I've seen a P0238 tripped is when the MAP sensor is unplugged, which happens fairly often since MOST everyones white plug is broken. Must be a more brittle plastic than other connectors. If your's is broke, put a zip tie on it.
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Old 03-22-2006, 01:05 PM   #5 (permalink)
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PO238 can set at Overboost which is a combination of not only boost levels but engine load as well.
At Idle, scan tool should sho 202 kpa from the boost pressure sensor.
If you would like the full troubleshooting table let me know.
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Old 03-23-2006, 07:23 AM   #6 (permalink)
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Yes, I'd like that full trouble shooting table. At idle, it was around 105 kpa

The engine load was at 99% according to the dtc snap shot.

And yes, the white plastic connector is broken (it seems to be a nice snug fit, even without the clip) but I honestly think that's not the problem. I ran the engine with it unplugged and got no readings on the scanner. Then I ran it with it plugged in and got different readings for boost and baro.

I bough a new map sensor at napa. real easy instal until I went to plug the harness in...she's a no fit. I remove the new sensor and see that plug receptacle has the plastic tabs in different locations than the factory map sensor. There's also a little note that came with the napa map sensor "part may be different in appearance than original part. However, it will function the same".... of course that's only true if you can install it .

I'm off to the stealer where I'll pay double for the map sensor
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Old 03-23-2006, 11:15 AM   #7 (permalink)
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well I survived the trip to the dealer. there was some confusion as I asked for a MAP Sensor. The dealer says it does not have a map sensor..... but it does have a boost pressure sensor....

Boost pressure sensor was the magic word to use. No wonder the MAP sensor from Napa didn't work
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Old 03-23-2006, 02:03 PM   #8 (permalink)
gmctd
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Wonder where Boost pressure is sensed - you know, where the sensor is installed?

'Course, I guess the Baro sensor would then hafta be called the FAP sensor - for Firewall Air Pressure......................
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96 Dodge 3500 cc 2wd drw 3.54 6sp......89 GMC 3500 cc 6wd drw 4.10 4L80E 205
5.9CTD 12v TST#10 plt SBC 13"............6.5TD, EFI, DSG, Max-E-Tork v2.0
DODGE makes it - CUMMINS shakes it.....Charge-air cooled, 3.5" ss exhaust
6 in a row makes it go..........................5000"lbs torque to the ground
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Old 03-23-2006, 07:56 PM   #9 (permalink)
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FAP sensor, eh?....but mine's an "F" motor.....


I think the BPS replacement did the trick. I didn't clear the stored codes yet. On a quick test drive, the truck repeated the surging thing at the first wot run. Second and third wot shots were fine. When I get a chance, I'll plug into the computer and clear the stored codes and take a look at my fuel rate. It wouldn't go past 63mm before. Hopefully it's better, but the old seat of the pants dyno is telling me not really.

thanks for the input, guys.

On another note, while I was at the dealership getting the bps, I saw my friend Lee. He told me that DTC U3700 is a communication error. Very nonspecific. But I had it and a couple guys here mentioned seeing it before.
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Old 03-23-2006, 10:51 PM   #10 (permalink)
gmctd
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F Baro sensor is mounted on the firewall - maybe the FWAP sensor, then?

Don't forget to compare Baro to new Boost in kpa
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tdp member #1505 - GMTDScan Tech, Autoenginuity help on-board......
96 Dodge 3500 cc 2wd drw 3.54 6sp......89 GMC 3500 cc 6wd drw 4.10 4L80E 205
5.9CTD 12v TST#10 plt SBC 13"............6.5TD, EFI, DSG, Max-E-Tork v2.0
DODGE makes it - CUMMINS shakes it.....Charge-air cooled, 3.5" ss exhaust
6 in a row makes it go..........................5000"lbs torque to the ground
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