You are here:

Chrysler Repair/'02 300m: codes 0138, 0158, 0172, 0175, 441


I have a 2002 300m that is overheating. changed thermostat coolant flushed engine. when overheats codes that come up are   po138
po175 the last time this happened i also got code po441 any help appreciated

Hi Rick,
The 138 and 158 point to the downstream oxygen sensors (located downstream of the catalytic converters) and says that the readings on their signals are at 12 volts instead of somewhere between 1 and 2 volts which suggests that the two signals are each shorted to "voltage".
It is unlikely that each sensor is bad identically and more likely that the wiring of the sensors are somehow both shorted to a 12 volt wire. The closest positioning of the wires involved is at the powertrain control module where at plug 1 (black) which has 38 pins there is a 12v wire on pin 32, and the two signal wires on pins 31 and 33. So begin by looking at the plug to see if the wires might have been damaged so as to contact one another. The other place they could be damaged is at a light gray color 14-pin disconnect where the wires are on pins 10, 11, and 12. That disconnect is located near the seam between the engine and the transmission on the upper left side of trans. There is an adjacent light gray connector but it has only 10 wires so be sure to find the 14-wire disconnect and examine the three wires on both sides. Also look along the harnesses between the powertrain control module plug and the disconnect and from the disconnect to the sensors for any signs of damage.
The 172 and 175 say that the fuel mixture on both exhaust streams is too rich and that may be a false reading due to the shorting situation and those may go away when you resolve the sensors.
The 441 is about the evaporation of fuel recycling system and says there is something wrong with a purging valve or its solenoid switch or the connecting vapor hoses between the fuel tanks and the charcoal canister that stores the vapors temporarily. There is an 18-step procedure for checking that out which I can copy and attach to an email which I would send to you directly but I need to know your email address. If you tell me it, don't use the @ symbol but rather use "at" of the address will be automatically erased from your follow-up question.
Those are my ideas at this point.

Chrysler Repair

All Answers

Answers by Expert:

Ask Experts


Roland Finston


Free fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

I answer questions seven days a week and respond to you in about 30 minutes. "Maxed Out" means I am answering another question, briefly unavailable, or asleep overnight, so try again later.

I have do-it-yourself experience (50+ years) and a library of 100 1982-2011 Chrysler factory shop manuals and 20 multi-manual Chrysler Corp. CD's.

I was voted "Top Expert" 2010-2015, here at AllExperts, and have answered 20,000+ questions.


Five decades as a 'do-it-yourselfer' on domestic and imported cars.

Yahoo Autos Group called The Chrysler Lebaron Club (co-moderator)

Advanced degrees in Physics/bruised knuckles

Awards and Honors
"Top expert" of 2010, 2011, 2012, 2013, 2014 and 2015 here at Allexperts. Quickest "average response time" at Allexperts (currently no. 1).

©2016 All rights reserved.