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Need help with Check Engine Light

4K views 16 replies 6 participants last post by  Take it as it rolls 
#1 ·
Check Engine light comes on and goes off by itself and sometimes it goes a week before it comes back on for a few days before it goes back off again. Car still rides fine and I have not noticed any performance changes.

Pulled out a scanner and I have the following 4 codes:

P0174
P1101
P0068
P0171

Any idea where I should start? Based on some Google searches it seems to be vacuum leaks or a MAF malfunction. Also seen some threads where it said ECM needed to be reprogrammed.

Any of you experience these codes on your N*?
 
#2 ·
I had the same problem. I checked the intake manifold bolts and they were loose. After tightening them I removed the MAF sensor, cleaned it in ethyl alcohol, rinsed it in hot water, and dryed it with a hair dryer. The problem has never returned.
 
#3 ·
#5 ·
Well... Light went back on for around 15 minutes and went back off by itself. Pulled the reader out and 2 codes returned:

P1101 & P0068

Problem only occurs when vehicle is started and its cold outside. Never have this issue in the summer so I did more reading and found this:

Bulletin No.: 09-06-04-032A

Date: August 06, 2009

Subject: Check Engine Light On, DTC P1101, P0068, P0171, P0174 (Reprogram ECM)

Models:
2004-2006 Cadillac SRX, XLR
2005-2006 Cadillac STS
Equipped with Engine RPO LH2
Please Refer to GMVIS

Supercede:
This bulletin is being revised to change the labor time information. Please discard Corporate Bulletin Number 09-06-04-032 (06 - Engine/Propulsion System)

Condition

Some customers may comment on an illuminated check engine light shortly after a cold start with no engine performance concerns. Upon inspection, DTC P1101 (Intake Air Flow System Performance) may be set. In some instances, DTCs P0068 (Throttle Body Airflow Performance), P0171 (Fuel Trim System Lean Bank 1) and/or P0174 (Fuel Trim System Lean Bank 2) may eventually set as a result of the DTC P1101.

Correction

Verify the condition. If the diagnostics in SI for the conditions described above do not isolate a fault, reprogram the ECM with the revised calibration that has been developed to address this condition.

Verify that the multiple diagnostic interface (MDI) that is being used is configured to the PC that will be used.

Warranty Information


((Table is not here, I couldnt copy and paste it, it says .4 hours labor.))

For vehicles reprogrammed under the 8 year/80,000 mile (130,000 km) emission controller warranty, use the table above.

..

My car only has 60k miles but since mine is a 2005 I guess this falls out of the warranty. What is this going to cost me?
 
#8 ·
#10 ·
Ethyl alcohol = ethanol = either cheap 100 proof vodka or grain alcohol at a whiskey store.

The ONLY reason you cannot drink 190 proof ethanol designed for gasoline additive use is that it is "denatured" - rendered unfit for human consumption - by the addition of stinky chemicals or just plain old gasoline.

If you were to take pure ethanol from a distillery on Monday and age it for 7 years in charred oak casks you would wind up with bourbon. Take Tuesday's output and add a denaturant and you have gasoline additive. (Simplistic, but the basic premise holds true)
 
#12 ·
Cleaned the MAF, Reinstalled and codes are back after re-start. Looks like I will have to schedule a visit to the dealer for ECM reprogram.
 
#13 ·
When is the last time the throttle body was cleaned? It seems to me that the codes you have indicate a mismatch between what the MAF senses for airflow and the physical position of the throttle. At its worst, I could restart mine three time and the code would clear.
 
#15 ·
With a scan tool such as the Autoenginuity you can read out the MAF signals as well as throttle position and other data and compare it with expected outputs as outlined in the factory service manual. Otherwise you might as well be another amateur floundering around with guesswork.
 
#17 ·
Well after scanning it with a Launch x431, we tried to get the reading for a MAF. 0Hz 0G/s. We went and checked a Sonoma of the same year and the MAF gave us a reading (forget the numbers but it read). The MAF on the Caddy has power and a good ground but still not reading. The boss also tried a new MAF and nothing changed.
 
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