Check Engine Light

H3 Specific Information

Check Engine Light

Postby trailerpup » Fri Jun 13, 2008 8:37 pm

Last week the check engine light came on. Before I could take the H3 in, it went out. 2 days later it came back on. Stopped at local auto parts store and used their scanner to pull the code p0171 (lean, bank 2). The next day I was going to take it in after work and when I started it up the light was off. So, I imagine the light cycles every few start ups? And, the code is still in the 'puter? Guy at auto parts store said to look for a loose vac line. Haven't found anything amiss. Somebody told me to run some injector cleaner with my next fill up or pull the mass air sensor and spray it with brake cleaner? I plan on taking it to the dealer on Monday. Thought I would get some thoughts from the forum over the weekend. Any info you all can provide is much appreciated!! It doesn't seem to be running any different than normal. I thought if it was running lean the temp gauge would be reading a little higher, but the needle is right were it always is. What do you all think? Thanks.


2007 H3, Volant CAI, 11,0000 mi
Last edited by trailerpup on Fri Jun 13, 2008 9:18 pm, edited 1 time in total.
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Re: Check Engine Light

Postby Robo » Fri Jun 13, 2008 8:51 pm

--------------------------------------------------------------------------------
TMI probably, but here you go.. :)


DTC P0171
Circuit Description
The powertrain control module (PCM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy and emission control. Fuel delivery is controlled differently during Open and Closed Loop. During Open Loop the PCM determines fuel delivery based on sensor signals without heated oxygen sensor (HO2S) input. During Closed Loop the PCM adds HO2S inputs and level of purge to calculate Short and Long Term fuel trim adjustments. If the HO2S indicate a lean condition, fuel trim values will be above 0 percent. If the HO2S indicate a rich condition, fuel trim values will be below 0 percent. The values for the Short Term fuel trim change rapidly in response to the HO2S voltage signals. Long Term fuel trim makes coarse adjustments in order to maintain an Air/Fuel Ratio of 14.7:1. A block of cells contain information arranged in combinations of engine speed (RPM) and engine load for a full range of vehicle operating conditions. The long term fuel trim diagnostic is based on an average of cells currently being used, but is capable of identifying a lean condition within a single cell. The PCM determines the cell based on the current engine speed and engine load. If the PCM detects an excessively lean condition, DTC P0171 sets.

DTC Descriptor
This diagnostic procedure supports the following DTC:

DTC P0171 Fuel Trim System Lean

Conditions for Running the DTC
• DTCs P0030, P0036, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0128, P0130-P0138, P0140, P0141, P0201-P0205, P0220, P0222, P0223, P0300, P0301-P0305, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496, P0506, P0507, P060D, P1106, P1107, P1114, P1115, P1133, P1134, P1380, P1381, P1516, P2101, P2119, P2120, P2123, P2125, P2127, P2128, P2135, P2138, and P2176 are not set.

• The engine is in Closed Loop status.

• The engine coolant temperature (ECT) is between -35 and +125°C (-31 and +257°F).

• The intake air temperature (IAT) is between -7 and +145°C (19.4-293°F).

• The manifold absolute pressure (MAP) is between 15-85 kPa (2.2-12.3 psi).

• The vehicle speed is less than 132 km/h (82 mph).

• The engine speed is between 400-5,700 RPM.

• The barometric pressure (BARO) is more than 70 kPa (10.2 psi).

• The mass air flow (MAF) is between 1-511 g/s.

• The fuel level is more than 10 percent.

• DTC P0171 runs continuously once the above conditions are met.

Conditions for Setting the DTC
• The Long Term fuel trim weighted average value is more than a calibrated value.

• The above condition is present for more than 2 seconds.

Action Taken When the DTC Sets
• The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

• The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC
• The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
• The current cell can be observed using a scan tool.

• Test for fuel contamination. Small amounts of water can be delivered to the fuel injectors and cause a lean exhaust indication. A lean exhaust indication can also be caused by too much alcohol in the fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

• The system will go lean if an injector is not providing enough fuel.

• A lean condition could be present during high fuel demand due to a fuel pump not pumping enough fuel or a restricted fuel line.

• Insufficient fuel in the tank or low fuel pressure may cause this DTC to set. Refer to Fuel System Diagnosis .

• Review the Failure Records with a scan tool. If an intermittent condition is suspected, refer to Intermittent Conditions .

Step
Action
Values
Yes
No

1
Did you perform the Diagnostic System Check - Vehicle?
--
Go to Step 2
Go to Diagnostic System Check - Vehicle

2
Important: Disregard any transmission symptoms, antilock brake system (ABS) indicators, and traction control system (TCS) indicators until any fuel trim faults are repaired. A fuel trim fault may cause default actions such as harsh shifts and illumination of the ABS/TCS indicators.

Are any DTCs other than DTC P0171 also set?
--
Go to Diagnostic Trouble Code (DTC) List - Vehicle
Go to Step 3

3
Turn the ignition ON.
Observe the Freeze Frame/Failure Records parameter with a scan tool and record the displayed data for this DTC.
Start and operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions observed from the Freeze Frame/Failure Records.
Observe the Long Term FT parameter.
Does the scan tool indicate that the Long Term fuel trim is more than the specified value?
23%
Go to Step 4
Go to Diagnostic Aids

4
Slowly operate the engine from idle to 3,000 RPM while observing the HO2S 1 and HO2S 2 parameters with a scan tool.

Does the scan tool indicate that the heated oxygen sensor (HO2S) voltages are within the specified range and fluctuating?
20-900 mV
Go to Step 5
Go to Step 6

5
Turn OFF the engine.
Visually and physically inspect the following items:
• The vacuum hoses for splits, kinks, and proper connections--Refer to Emission Hose Routing Diagram .

• Fuel contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

Did you find and correct the condition?
--
Go to Step 9
Go to Step 8

6
Turn OFF the engine.
Inspect the HO2S for proper installation. Refer to Heated Oxygen Sensor 1 Replacement and Heated Oxygen Sensor 2 Replacement .
Ensure that the electrical connectors and wires are secured and not contacting the exhaust system.
Did you find and correct the condition?
--
Go to Step 9
Go to Step 7

7
Test the HO2S high signal circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?
--
Go to Step 9
Go to Fuel System Diagnosis

8
Operate the engine at idle.
Inspect for the following conditions:
• Missing, loose, or leaking exhaust components, from the HO2S forward--Refer to Symptoms - Engine Exhaust .

• Vacuum leaks at the intake manifold, the throttle body, and the injector O-rings

• Air induction system and the air intake ducts for leaks or for a missing air filter element--Refer to Air Cleaner Assembly Replacement and Air Cleaner Resonator and Outlet Duct Replacement .

• Evaporative canister purge lines plugged or obstructed

• Properly functioning fuel injectors--Refer to Fuel Injector Diagnosis .

• Crankcase ventilation system for leaks--Refer to Positive Crankcase Ventilation Hose/Pipe/Tube Replacement .

Did you find and correct the condition?
--
Go to Step 9
Go to Symptoms - Engine Mechanical

9
Clear the DTCs with a scan tool.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running in the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?
--
Go to Step 2
Go to Step 10

10
To verify that the performance of the catalytic converter has not been affected by the condition that set this DTC, perform the Repair Verification for DTC P0420. Refer to DTC P0420 .

Did you complete the procedure?
--
Go to Step 11
Go to DTC P0420

11
Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?
--
Go to Diagnostic Trouble Code (DTC) List - Vehicle
System OK
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Re: Check Engine Light

Postby trailerpup » Fri Jun 13, 2008 9:15 pm

And to think that BITD I could adjust the points with a matchbook cover. I am getting old. Thanks Robo!!
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Re: Check Engine Light

Postby f5fstop » Sat Jun 14, 2008 10:57 am

If you can, take it to the dealer, but the code will automatically clear in around 80 engine cycles (engine cycle=engine start to a specified engine operating temp, then back down to another coolant temperature).
Personally, if it was me, and the light was now off, I would wait until another tank of fuel had been run through the engine, before leaping to the dealer. It might be a simple fuel related problem, but if it comes on and stays on, go to the dealer as soon as possible.
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Re: Check Engine Light

Postby trailerpup » Sat Jun 14, 2008 4:11 pm

Light was off this morning when I started it up. I got a bottle of injector cleaner and added it when I filled up. Stopped at the bike shop to get some thing for my mountain bike. Then headed 15 miles out of town to see the rock races. No problems, no CEL. After a few hours of watching the races (those guys are crazy) I decided to head home. When I started the engine the CEL light was back on. It seems to come and go. I would think the thing would just stay on. I will probably stop at the dealer on the way home from work on Monday. Maybe tomorrow I will clean the mass air sensor and see what that does. Thanks for the feedback.
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Re: Check Engine Light

Postby Steve #1 » Sun Jun 15, 2008 5:23 am

trailerpup wrote:Somebody told me to run some injector cleaner with my next fill up or pull the mass air sensor and spray it with brake cleaner?


DO NOT USE BRAKE CLEANER ON THE MASS AIR SENSOR! The MAS has a special coating on it that will be stripped off by brake cleaner. ONLY use CRC Mass Air Flow Sensor Cleaner.
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Re: Check Engine Light

Postby trailerpup » Sun Jun 15, 2008 1:46 pm

O.K. I'll get a can of "CRC Mass air flow cleaner" as suggested and clean it this afternoon (I will also go over the intake, etc. to look for leaks or loose vacuum connections). Thanks Steve#1. I thought I would put this problem up on the forum to document my experience with a P0171 code. Hopefully, it will help another X-cluber in the future. I'll post back the results of cleaning the sensor. Thanks again for the help.
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Re: Check Engine Light

Postby kb3ejw » Sun Jun 15, 2008 4:06 pm

robo,u weren't liein that was intirely to much info...

where in the world did u get that stuff?????

have a great day
why do i get the hand me downs?
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Re: Check Engine Light

Postby trailerpup » Sun Jun 15, 2008 6:57 pm

Went down to the auto parts store and picked up a can of MAS cleaner. Cleaned it there in the parking lot. Light was still on when I restarted. Stopped by the conveinence store for a couple of minutes. Then went to the quarter car wash. Light still on. Headed over to the supermarket. When I came out and started the H3 the light was still on. Then, a few minutes after driving the light went out. :/ Came home and it has been parked for the last few hours. I'll see what the light does when I go to work in the morning. I can't figure out... if seems like it would take more cycles for it to reset itself. I am thinking that the code is still logged in memory and if there are no more problems it will clear the "history" memory after 80 cycles? We'll see.
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Re: Check Engine Light

Postby Seth » Mon Jun 16, 2008 1:57 pm

kb3ejw wrote:robo,u weren't liein that was intirely to much info...

where in the world did u get that stuff?????

have a great day

Robo works at Penske Hummer Dealer as a parts guy and has access to all that cool tech info.
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Re: Check Engine Light

Postby Robo » Mon Jun 16, 2008 3:23 pm

kb3ejw wrote:robo,u weren't liein that was intirely to much info...


:lol: :lol: :lol:

Seth wrote:Robo works at Penske Hummer Dealer as a parts guy and has access to all that cool tech info.


:yup: :D
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Re: Check Engine Light

Postby f5fstop » Mon Jun 16, 2008 6:02 pm

Why go after the Mass airflow sensor? I would be adding some fuel anti-freeze, a can of techron and let the fuel in the tank burn out. Then a new fill and see what happens.
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Re: Check Engine Light

Postby trailerpup » Tue Jun 17, 2008 6:49 pm

I think it was the MAS. When I cleaned it I did notice some small particles that looked liked blue metallic paint on the MAS body. Don't know where they came from. The light has been off since Sunday afternoon and no performance issues. If it comes back on, I will revive the thread. Hopefully, if someone has the P0171 code they will search and see this thread. Once again, thanks for all the good info!!! :)
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Re: Check Engine Light

Postby Hunner » Tue Jun 17, 2008 6:52 pm

Are you sure you torqued the exhaust back up to the head reeeel gud after the header experiment? Hopefully you solve the problem but that was my thought on that.
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Re: Check Engine Light

Postby trailerpup » Tue Jun 17, 2008 7:41 pm

Darn it Hunner, you're gonna put the Mojo on me.... :lol: Oh, the header, that was a fun couple of weeks, though. To set the record straight, I did not punch out the #1 cat as some have done on Colorado forum!! Somebody on the Elcova forum said I did, but since I am banned because of my "hatred of the H3, and my love of the Land Rover LR street machines" I can't set the record straight. I drove 1400 miles pulling the Airstream Bambi over here to Colorado and I was thinking about those bolts all the way over. I checked them first thing when I got to my new home. I know when I torqued them down after my affair with the header I was being cautious :/ But, they are good to go.

I didn't know a little light bulb could affect my psyche so much!! :cry: But, as long as it is not glowing, I am!!

So, the P0171 code... can come up as bank 1 or bank 2.... what's the diff??
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