Engine code p0171 and p0174

[Mchaney9900]

Engine codes: p0171 and p0174
The car is not throwing any other codes.

Hi, I am searching for assistance and advise from anyone that has had the same problem. I have a 2008 XLR, with 39000 miles. The engine light came on yesterday. Took it into the dealer today and the dealer said it showed code p0171 and p0174. They told me it was caused by my new Corsa Exhaust. I reminded them that I had the car in the shop in November 2011 for the same thing, same codes and that was before I changed the exhaust system. They than took the car for a test drive and tried to duplicate the problem. They said that the condition occured at 70 mph @ 1700 rpm and cound not fail any components. Mapp system checks OK, road tested and tried to recreate the failure and could not. The codes were cleared and sent me on my way. They said they would see how long it takes to happen again. They told me the same thing in November 2011. Since than I have driven the car 500 miles. The cars does not show any other problems or symtoms, runs great. Does anyone have any suggestions. Please help!
Thanks
Matt

[ccclarke]

Your dealer's diagnosis is incorrect regarding your exhaust system causing these codes as you rightly pointed out to them. Other than a DTC number, did they explain what these codes mean? Probably not, since that wouldn't have made sense to you or them.

P0171 and 174 are related to the injectors on Banks 1 & 2 reporting a lean condition, meaning they aren't supplying enough fuel. A faulty MAF can cause this, so that was a proper component to inspect. There is a procedure to diagnose an intermittent condition in the shop manual.

The Engine Control module regulates the air/fuel metering to provide the optimal combination of fuel economy, performance, and emissions output. There are two types of fuel delivery: Open and Closed Loop.

When in the Open Loop mode, the ECM disregards the oxygen sensor data for determining fuel delivery. In Closed Loop mode, the O2 sensor data is used. If the ECM determines there is ann excessively lean condition present, these two codes are flagged and the MIL light is illuminated. There's a bunch of parameters that can create this condition, but the bottom line is, if it happens again, get a second opinion from another dealer. There are ways to trap the data parameters with a Tech 2 and a tech who knows how to interpret them with the manuals.

CC

[Mchaney9900]

CC, Thanks for the feedback. I will take your advise. I have an appt. to take it into another dealer in Baltimore for a second opinion. The MIL came on again yesterday. Hopefully, Chesapeake Cadillac will be able to resolve the problem. I will take a copy of your response with me and hope that it helps.

[XLR I FL]

Chesapeake is a great dealer!!

Did you or the previous owner put a non OEM air filter in that requires oiling?

If so, as CC pointed out over oiling will damage the MAF sensor and cause the codes. There is a shop bullitin on this issue.

Cleaning or replacement of the sensor and cleaning and correctly oiling the filter should fix it and make the codes go away.

Regards

Jerry

[ccclarke]

One important thing to keep in mind when communicating with the dealer is that the Corsa exhaust system (as long as it hasn't been modified) is a GM-approved accessory, meaning its form, fit and function should not interfere with the proper operation of the vehicle in any way when installed per the manufacturer's instructions.

A second opinion should bear that out. Personally, I'd add some fuel injector cleaner and see if it clears the MIL lamp after a couple of ignition cycles. I do this once a quarter and have had good results. My fuel economy can still reach 28 mpg in long-distance highway driving. My vehicle has almost 70k miles on it and is equipped with a Corsa system.

CC

[Mchaney9900]

The dealer replaced the MAS and the code have not returned. I have driven the car over 500 miles and everythings seems to be fine.
Just waqnted to post an update.

[ccclarke]

Thank you for following up on this problem with the MAF replacement solution. It's always nice to see a resoluton to a problem, and will undoubtedly be of help to anyone else with the symptoms you described.

CC

[Mchaney9900]

Well the codes p0171 and p0174 are back. I hace driven about 600 miles since the Mass Air Flow sensor was replace on 5/30/2012. I took it in to the dealer on 11/14/12 and they wanted to keep the car to run more test. This is getting frustrating. I have been back to the dealer about 5 time for this issue and it keeps coming back.
I'll let you know what they find once I get the car back.

[CadillacCustSvc]

Originally Posted by Mchaney9900

Well the codes p0171 and p0174 are back. I hace driven about 600 miles since the Mass Air Flow sensor was replace on 5/30/2012. I took it in to the dealer on 11/14/12 and they wanted to keep the car to run more test. This is getting frustrating. I have been back to the dealer about 5 time for this issue and it keeps coming back.
I'll let you know what they find once I get the car back.

I apologize for any frustration caused by this issue. Please PM us if you continue to have issues with your XLR. I hope they are repaired quickly.

Matt,

Cadillac Customer Assistance

[xlrlist01]

Originally Posted by Mchaney9900

Well the codes p0171 and p0174 are back. I hace driven about 600 miles since the Mass Air Flow sensor was replace on 5/30/2012. I took it in to the dealer on 11/14/12 and they wanted to keep the car to run more test. This is getting frustrating. I have been back to the dealer about 5 time for this issue and it keeps coming back.
I'll let you know what they find once I get the car back.

Make sure the connector block has been subjected to a thorough inspection and use some proper contact cleaner on it (not WD40). Given it worked OK for a (short) while, the symptoms suggest a problem at the sensor end. The fact that the fault went away suggests they are working in the right area and the problem is affected by the work being done. Assuming the dealership are good at their job, they will know this anyway.