2001 Cadillac DeVille Logo
Posted on Jun 09, 2011
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My Cadillac deville keeps popping codes p0171 and p0174. Just changed the MAF didn't help. Now car runs bad and getting horrible gas mileage. Any ideas please.

3 Answers

Aobd2

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  • Cadillac Master 1,049 Answers
  • Posted on Jun 17, 2011
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Hi, this is an obd2 trouble code table, can help you understand the code. and this tool connects this tool can solve your problem,hope help.

amyfan

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  • Expert 191 Answers
  • Posted on Mar 21, 2014
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GM Tech2 can solve your problem,hope help.

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Anonymous

You don't have MAF codes

Are you not aware you start with & diagnose
& resolved all code related issues first?

I don't see how you could change a MAF as you
won't know how to test it

PO-171 System too lean (Bank 1)
PO -174 System too lean (Bank 2)

That sounds like a vacuum leak that effects
both sides of motor

The front O2 Sensors get replaced at 100,000 miles

If that was done don't do them again unless they fail

80% of O2 Codes are vacuum leaks that lean out
the fuel mix. The Sensors are just reporting what they
see. It is up to a mechanic to find out why

When they report lean then the ecm adds fuel by
increasing injector pulse width thus bad gas mileage

I suggest buying a $50.00 code reader & study OBD2
Systems on the internet.

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Related Questions:

0helpful
1answer

I have a 2000 Cadillac Deville with 180k miles. I've been getting P0171 and a P0174 code. Yet there is no vacuum leaks. I replaced the MAF and still its idles rough once it heats up. Any suggestions?

Have you not Googled the Codes PO171 & PO174
to learn the problem ?

I would suspect you never changed the front O2 Sensors
at 100,000 miles & they both have now failed

The MAF shouldn't have been the issue

You may also have converters that are worn out
with a 14 year old vehicle

Are you changing Spark Plugs every 3 years ?

A rich fuel issue will drive the O2 lean also
Need to look at Fuel Trim on scan tool & other data
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2004 Cadillac DTS engine codes P0171 & P0174

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Ford Taurus Engine Light is: P0171 & P0174. I am thinking a MAF Sensor

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The codes mean the ECM can not make the injectors rich enough to make the O2 sensors switch back and forth.
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PO174 P0171 CODES 2004 CADILLAC DEVILLE

The code P0171 and P0174 have the same mean that "System Too Lean"
OBD2 code scanner
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I have an 02 deville I just gave it a tune up changed.both ignition coils and the two head valve gasket n now it still reads code p0300 and 2 new ones p0171 and p0174. Can someone help and my check coolant...

The floats on those reservoirs are bad to stick because of the sealer you have to keep adding to the fluid. I got mine unstuck by removing it the reservoir and thoroughly cleaning it with dish soap. Good luck. I could not see a way to remove or replace the float.
5helpful
1answer

My cadillac deville has the following engine codes when hooed up: P0106, P0121, P0171, P0174, P0335, P0340, P0385, P0442, P0506, P0506, P0507, P0601.

click on the below links for code details.
P0106

P0121

P0171

P0174


P0335


P0340

P0385

P0442

P0506

P0507

P0601.

all of the above codes seem to have a common cause, they all list a bad ecm (computer) as being a cause, and the last code P0601 points specifically to a bad computer. sorry for the bad news, hope this helps.
0helpful
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My 2001 cadillac deville keeps giving me dtc code system to lean

Anytime I get a too lean DTC I first change the fuel filter if it hasn't been changed in awhile. You'd be surprised how many times this has helped.

Good Luck with it.

Bob
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Codes P0171, and P0174 bLean on a 98 Navigator. Any ideas?

mass air flow sensor is not the problem, I had the exact same problem and have done much research on this. Check the PVC rubber hoses, especially the elbows for cracks. You probably noticed your gas mileage has been horrible too. Hope this helps
14helpful
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4 codes P0171,P0174,P2195,P2197

Hi
171 system too lean
174 system too lean
2195 - 02 ozygen sensor signal stuck lean Bank1 Sensor 1
2197- 02 ozygen sensor signal stuck lean Bank 2
Sensor 1
The 2 front 02 sensors are located on the front of
the exhaust manifold.
Should solve problem and increase gas mileage.
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