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TOPIC: engine light won't go away

engine light won't go away 3 years 10 months ago #82362

  • Jay86
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Hey Everyone, new to the site, hopefully someone has some advice?

I have a 2004 pt cruiser 2.4lt touring. The engine light has been on for about 3-4 years now and won't go away no matter what we have tired!!

We have replaced o2 sensors, cam and crank sensor, throttle position sensor, new fans, and sent the computer away to be tested. and still the engine light is on. when scanned fault code p0481 cooling fan control circuit, p0031 o2 sensor #1, poo37 o@ sensor #2. Also have the airbag light comes on and off about every 1-2km.

Before removing the computer almost every warning light on the dash was on (felt like i was driving a mobile xmas tree, even had its own chime) but after putting it back in only engine and airbag light?

Car runs and drives fine.
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engine light won't go away 3 years 10 months ago #82363

  • gooddog
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hi, our car was away for 9 weeks, engine light on, computer sent away, all tested ok (even more infuriating) was A LOOSE EARTH WIRE to alternator, have you tried an auto electrician?
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engine light won't go away 3 years 10 months ago #82365

  • i2s2bme
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  • Colin & Joan
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Hi, welcome
Where are you located, Town and state?
Colin & Joan

UHF: Ch19
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Club Mail: PO Box: 357 Figtree, NSW 2525
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engine light won't go away 3 years 10 months ago #82366

  • PTmunji
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  • Steve & Moni
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Try to do a computer reset-
Remove negative & positive battery leads from the battery, then join the leads together (but ONLY the leads, without touching the battery)
together for 2 minutes. Then reconnect the leads to the battery.
This will reset the computer to factory zero, and then see what happens.

Airbag light is a totally different issue (there are lots & lots of posts here about airbag lights, have a look)
Steve & Moni & her Bat-Cruiser
Last Edit: 3 years 10 months ago by PTmunji.
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engine light won't go away 3 years 10 months ago #82376

  • Dopo
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Hi Jay

I have 3 PTs and do my own work so have got to know these lovely cars :blink: and some of the weird faults typical of Chrysler cars, not just PTs.

I had one with the common issue of P0031 02 sensor #1, P0037 faults. There is a heap of information on the USA PT sites about these issues and they often suggest it can be bad O2 sensors (there are two of them ) or a bad earth, all those black wires bolted up on the inner left guard just next to the air cleaner box. Make sure the connections are clean and tight.

Unfortunately it is often the Powertrain Control Module (PCM) or what most call the main engine computer that sits up on the passenger side of the firewall. The PCM controls the operation of the O2 sensors and many other things which are normally controlled by relays in other cars.

On a car I worked on, after replacing the O2 senors with new factory ones, I checking all the wiring but still the faults :(
I ended up replacing the PCM with one from a wrecker. Cost $250. The PCM has to programmed to the car which can only be done by a Chrysler dealer. They have the software and the access codes :angry: Cost about $200 - $300 to get reprogrammed.

When you say the computer was tested? How was it tested? The only real way to do that is try it in another car, if the same faults come up on the other car yep then its the PCM. Or it has to be tested on a proper simulator that they can test all functions of the PCM in real time under real loads. Warning, don't buy a exchange PCM from those USA web sites. Most are just cleaned up units from a wrecker. Not worth the risk. Try an Australian wrecker or if you have to get a new one or an exchange PCM try the USA Chrysler dealers. Many have online shops.

The other thing it might be and given you are having issues with the cooling fans, is the what I will call the fuse box, That black thing just behind the air cleaner box. It has a circuit card inside which controls other things like the air con compressor etc. It is known to fail and will cause weird things as well. If you are good with the tools, or know someone who is, pull it out, pull the fuse box apart to get to the ctt card and look for burnt bits. Often jump start done wrong can cause damage to this part.

This part can be replaced as a swap out. Usually no need to reprogram to the car, I have done it before. You might be lucky and pick one up from a wrecker but make sure the part numbers are the same on the replacement one to the one in your car. There are variations between models. Alan at sells exchange units if you can't get one from wrecker. Again check out the USA PT forums, lots of info on known issues with the fuse box.

Good luck, Dopo
Last Edit: 3 years 10 months ago by Dopo.
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