96' 850 GLT Long saga of P0140 P0133 MVSOLVED

DARK_BLU · Post by **DARK_BLU** » 31 May 2015, 19:29

Greetings,

I have a 1996 Volvo 850 GLT/NA. It currently has 306,500 miles and the gas mileage is not as good as it's been. Being that the car has this high of mileage, I wouldn't think of it accept the CEL has come back repeatedly for both front and rear 02 sensors. Rear 02 sensor was first replaced in March, 2014. Front 02 sensor was replaced in February, 2015. P0133 and P0140, CEL appeared. Tried hard ECU reset. P0140 has not returned by P0133 returned twice. Reset twice with code reader. Peachtree Imports in Peachtree City, GA has not yet found and resolved why this keeps happening with new 02 sensors in place, but they indicated that an ECU replacement would be "expensive". I have not replaced the ignition coil, yet but have no codes indicating that's the problem.

Did some research on ECU replacement. I contacted Bill at Voluparts, here in Atlanta, GA. and he has a used '97 ECU for $125 (#0 261 207 077) that he indicated matches up to my current ECU, which is #0 261 203 077. I've read in numerous places that I can't just plug a new ECU in and the car will start and run right. I've heard that the ECU is specific to the car. So I have a questions, which I asked Bill and haven't yet received an answer (they are closed on weekends):

1. If I plug this 97 850 ECU in my car, will it start and will the ECU learn my car and make it run properly without having to be programmed by a dealer?

2. The used ECU that he wants to sell me is from a 97 850 manual, non-turbo. Does it matter that my car is a '96 850 manual, non-turbo?

3. Should I abandon this ECU replacement and just do a hard reset/disconnect negative battery cable for 30 mins. Should I replace the ignition coil instead of the ECU?

Appreciate the feedback. I'm not rich, so I need a workable solution on my budget. I can either buy an ECU or an ignition coil this week, but not both. Nothing in the paperwork indicates that Bosch 02 sensors were installed, so I don't know if the problem is Chinese 02 sensors or not.

DARK_BLU · Post by **DARK_BLU** » 31 May 2015, 19:33

I should also mention that the MAF was replaced, that the wires and plugs were checked and indicated to be fine and that both front and rear 02 sensors were replaced, but the P0133 has returned twice since then. The P0140 has not returned since the last code reader reset.

Post by **Ozark Lee** » 31 May 2015, 21:27

The ECU's pre '99 don't care what car they are in. There is no unique information about the car hard encoded into the module.

So long as the donor module has the same emissions stuff (SAS, EGR, etc) it should be plug and play. You may be able get around the SAS if the donor car had it - it will be a bit trickier than just soldering in the diodes though since I think it needs to have the valve plugged in to not set the CEL.

...Lee

Post by **atucker1** » 31 May 2015, 21:45

Also, just FYI, if you're really on a budget, an ECU at my local pick n pull is 50 bucks. You could pull it yourself and save 75.

DARK_BLU · Post by **DARK_BLU** » 31 May 2015, 21:52

When I contacted Bill at Voluparts to ask if he had an ECU that would match my car, he asked for the letters and number on the right side of my current ECU to determine if the one he had would match. He indicated that this number would provide him with the info he needed to determine if the one he had would work in my car. In the pic I sent him, it shows GW.2 Then he replied, indicating that he has that used ECU from a '97 that is a #0 261 203 077. So, will I have to take it to a dealer to get them to copy the info from my current ECU or can I just plug it in and the car will run?

DARK_BLU · Post by **DARK_BLU** » 31 May 2015, 21:53

atucker1 wrote:Also, just FYI, if you're really on a budget, an ECU at my local pick n pull is 50 bucks. You could pull it yourself and save 75.

That would be great, as my ECU has a lever, and once the lever is pulled, it just comes out. The new ECU would go in the same way. Problem is, I'm in Atlanta, GA, not Washington State.

Post by **abscate** » 01 Jun 2015, 04:26

DARK_BLU wrote:I should also mention that the MAF was replaced, that the wires and plugs were checked and indicated to be fine and that both front and rear 02 sensors were replaced, but the P0133 has returned twice since then. The P0140 has not returned since the last code reader reset.

You have to. Run through your car looking for vacuum leaks before you look at The ECU. Replace those wires and plugs depending on mileage. It's also possible for the coil to give a good blue spark on test, but fail under load. The guys pointing you to the ECU have given up.

Are you using OEM oxygen sensors or what the mechanic buys? There are cheap knockoffs in Bosch boxes that work about 1/3 the time.

OBD guides you to engine problems but does not tell you what part is bad, especially in the complex engine management system.

draser · Post by **draser** » 01 Jun 2015, 06:30

Your codes, especially the second one, may point to a wiring problem as well. Assumming you installed OEM sensor, check connector and wiring condition from connector into ECU. If wiring continuity is found good then check ECU grounds and power into ECU. If all that checks then yes, try another ECU.

Post by **erikv11** » 01 Jun 2015, 07:00

So now there is only one code and it is p0133, correct?

This does not sound like an ECU problem, it sounds like a vacuum leak, or maybe an exhaust leak, or the rear oxygen sensor or its connector. As stated, ECU problems are very rare on these cars, if you are on a budget then would stop looking at the ECU for now.

I also don't see a good reason to suspect ignition components (coil, plugs, wires), can somebody explain that to me?

If you do end up getting another ECU, there is nothing complicated about installing it. The last thee numbers need to match up, the emissions equipment needs to match up on the two cars (this likely comes down to whether or not the two cars have SAS, i.e. an air pump, as very few 96 model cars had EGR), after that you just pull out one ECU and put the other one in. No programming needed. Ever.

DARK_BLU · Post by **DARK_BLU** » 01 Jun 2015, 11:47

I found a disconnected vacuum hose. The only place it can reach or connect to is something underneath the battery tray, so I connected it there. Will hold off on the ECU replacement to see if I get a CEL and if the good gas mileage comes back. Peachtree Imports claimed that the wires and plugs were fine but I don't trust that. I'll replace the wires and plugs. Bougicord is best for plug wires?