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sprinkles08, ASE Certified Technician
Category: Chrysler
Satisfied Customers: 21440
Experience:  ASE Master & Advanced level certified, Chrysler Master Certified, Trans and Hybrid Specialist
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Chrysler: All of the following have been replaced in the last

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All of the following have been replaced in the last 3 days on my 2005 Pacifica/3.5 L engine (130,000 mi.):

P0508: Idle Control System Circuit Low
P0113: Intake Air Temperature Circuit High Input
P0132: O2 Sensor Circuit High Voltage (Bank 1 Sensor 1)
P0138: O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)

These fault codes return after being cleared. It runs fine at high rpm, but it idles very roughly and sometimes hesitates upon beginning to go/drive. This morning, I took it to a dealer (18 mi.), but it idled fine for the service manager, and it still showed the codes after being cleared. I asked if he thought it could be related to carbon buildup or a leaking exhaust system, which he believed it might. Midas inspected it and found no problems with my exhaust system.
Hello and welcome to JustAnswer!

I'm assuming the IAC, IAT and oxygen sensors are what was replaced?

P0508 sets when the IAC current falls too low. This can be the IAC itself, a wiring issue, or the powertrain control module (PCM). If the IAC has been replaced with a known good part and the same code is setting then the most likely cause would be wiring, likely a short to ground.

P0113 sets when the IAT's signal circuit voltage goes low. This again can be the sensor, a short to ground on the signal circuit, or the PCM. If the IAT gas been replaced with a known good sensor and the same code is setting then the most likely cause would be wiring.

I would make sure the IAT and IAC are plugged in correctly. They both are a two wire connector and are keyed the same and it's possible to get the connectors switched around. If the IAC connector is plugged into the IAT and the IAT connector is plugged into the IAC then it's going to set codes for each.

The most likely cause for the oxygen sensor codes would be the sensors, although it could be wiring. If the repair wasn't done at a dealer then it's unlikely they used the correct sensors. This uses an NGC type powertrain control module which is sensitive to the resistance characteristics of the oxygen sensors. Aftermarket sensors aren't compatible with a Chrysler vehicle using an NGC controller, if Midas didn't purchase the sensors from a dealer then they are almost guaranteed to set codes.
Customer: replied 3 years ago.

The IAT and the IAC are no longer showing a fault code, but the O2 sensors still are. They were installed by Firestone in Livonia, MI. I will call them first thing tomorrow AM. When I drove it home from Midas this afternoon (They found nothing wrong with the exhaust.), it ran as if there was no problem. However, when my grandson ran the diagnostics, it was still showing the O2s. I will get back to you tomorrow AM after I talk to Firestone. Thanks.

I had guessed that they were replaced at Midas since you mentioned them being involved at some point, but I would still venture to say that the Firestone shop still probably would have used aftermarket sensors. If you have a receipt from that repair there should have been part numbers on it, we may be able to decipher what they used if you happen to have the receipt.
Customer: replied 3 years ago.

No, I looked at the receipt hoping they would be there, but they were not.

I was hoping so too. Normally all parts used would be itemized on the customer receipt copy.

If you call them and ask them about the oxygen sensors I would approach it gently and ask about brand and maybe even part number, without mentioning in the beginning anything about them needing to be Mopar. I hate to imply someone I don't know would be dishonest, but I wouldn't doubt they'd just tell you the sensors were Mopar when they aren't if they know that's what you're asking.
sprinkles08 and 3 other Chrysler Specialists are ready to help you
Customer: replied 3 years ago.

Firestone in Livonia put Bosch O2 sensors (# XXXXX and #13937) in my Pacifica. I am in touch with their consumer affairs corporate office. I am asking for my money back, minus the engine diagnosis.


Thanks for your help.