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2000 Volvo S40 Hard Start Low Idle

Help, Advice, Owners' Discussion and DIY Tutorials on S40 and V40. In this forum you'll find S40/V40-specific owners asking and answering questions on maintenance, ownership, repairs, tutorials and almost every do-it-yourself thing you can do to save money owning these Volvos.

1996 - 2004 S40
1996 - 2004 V40

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Year and Model: 2000 S40
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2000 Volvo S40 Hard Start Low Idle

Post by Porkers » Fri Aug 31, 2018 2:39 pm

Hi, first time poster here. I just recently purchased a 2000 S40 with 108k on it. It had codes P1446 P0037 P0505 P0245 P0031 P0130 and P0445. It would start after 10-15 revolutions and run rough. It would stall if I didn't keep my foot on the gas. My reader said to change the PCV valve. I did that job and nothing changed. I checked for vacuum leaks and I absolutely cannot find any. I tried changing the IAC valve and MAF sensor. Now I have a MAF code. So I put the old one back and I still have that code. So I thought that it had to do with the purge valve because of the P0445 code. So I checked that I found that it wasn't sealing. I replaced that, but no change. So I checked the plug and I'm only getting 3.4V on the power side. So I did my own power setup to see if the low voltage was the problem. I hooked the power side to the battery and the ground side to the wire going to the ECM and the idle evened right out. No problems at all. So I go to clear the codes, shut off the car, clear them, and start it up again. It took a second to catch, but nothing like before. And the check engine light stayed off for maybe 5 seconds and then it started running rough again. I went out to check that my wires were still connected. They were fine. I go and check the codes again, and now it's all the same codes, just except for the P0445 code! But I can disconnect the wires, then reconnect them and it seems to completely smooth out. After some more looking, the IAC plug is also low, like 2.0V. Could that be why it's trying to stall? Is their wiring connected? Is there anything else in their circuit? Any help is appreciated. Thanks

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Re: 2000 Volvo S40 Hard Start Low Idle

Post by RickHaleParker » Sun Sep 02, 2018 11:40 pm

? Is their wiring connected?

Yes .......
System relay Feeds current to:
engine control module (ECM).
fuel pump
crankcase ventilation's heater
Turbocharger (TC) control valve. ... P0245
evaporative emission system (EVAP) valve .... P0445
Ignition coils
idle valve (IAC) .... P0505
both heated oxygen sensors (warm-up) ... P0031 P0037 P0130
mass air flow sensor (MAF)

You might want to go digging in the Fuse/Relay box. The system relay is the one in the rear driver's side corner of the relay box. symptoms are pointing toward a problem on a main electrical buss.

Platform: P80 1998 C70, B5234T3, AW50-42, Bosch Motronic 4.4, Special Edition package, Plant: Uddevalla Sweden.

Platform: X40 (Nedcar) 2003 S40, B4204T3, AW55-50/51SN, Siemens EMS 2000. Plant: Born Netherlands.

Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0, Plant Torslanda Sweden.
1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

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