P0137 & P0300

lohanso · November 27, 2007

Replaced the cat a few months ago (97 Sierra) and the old one was empty,all the catalyst went into the muffler the mech said. The truck ran fine until I took a 800 mile trip. On the way home them truck started losing power and surging a little. Trouble codes came on.

Had to change out the throw out bearing, clutch, and pressure plate (it was time). When I started the vehicle to back it into the garage it coated the garage floor with cat fines.

While changing the clutch ect. I was able to shake out a couple of large handfuls of catalyst chunks. Blew through the exhaust pipe with a compressure and feel like there is no restriction (now). Can still hears some small chunks rattling around ...swing it up and down until no more would come out. All the chunks came out the cat side of the muffler.

Could this both cause the codes and perhaps fix the problem ?

jrrod2004 · November 29, 2007

It is very possible that those codes showed up, I would have to do more research when my DealerWorld comes back online........

jrrod2004 · November 29, 2007

for Error Code P0137, it sounds like that sensor went out, here is some related information:

DTC P0137 HO2S Circuit Low Voltage Bank 1 Sensor 2

Circuit Description

The VCM supplies a voltage of approximately 0.45 volt (450 mV) between the HO2S High and HO2S Low circuits.

Important

If the voltage is measured with a 10 megaohm digital voltmeter, the voltage may read as low as 0.32 volt. The Heated Oxygen Sensor (HO2S) varies the voltage from approximately 1.0 volt (1000 mV) during rich conditions to 0.10 volt (100 mV) during lean conditions.

When the HO2S temperature measures below 360°C (600°F) the sensor will not produce any voltage. The sensor will behave like an open circuit. This will result in an open loop operation.

The HO2S heater provides for a faster sensor warm-up which allows the sensor to become active in a shorter period of time. The sensor will also remain active during a long extended idle. The DTC P0137 determines if the HO2S or circuit is shorted low by checking for a lean condition during a steady throttle and power enrichment (PE). This DTC is a type B DTC.

Conditions for Setting the DTC

The following conditions will set the DTC:

No TP sensor DTCs
No EVAP DTCs
No IAT sensor DTCs
No MAP sensor DTCs
No ECT sensor DTCs
No MAF sensor DTCs
No intrusive test in progress
No device controls active
The system voltage measures at least 9.0 volts.

Test Enable Lean Test

Closed Loop Low MAP not active
Closed Loop
Air to fuel ratio is at least 14.5 but less than 14.8
The TP is greater than 5% but less than 99%
The above met for 5 seconds
Related HO2S DTCs not active since code clear

Test Enable PE Lean Test

A Closed Loop
The Power Enrichment mode active
The high speed fuel cutoff not active
Related HO2S DTCs not active since code clear
Time elapse since test enable is greater than 2 second

Action Taken When the DTC Sets

The VCM turns on the MIL (Malfunction Indicator Lamp) after 2 consecutive failures.

Conditions for Clearing the MIL or DTC

The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
Use a scan tool in order to clear the DTCs.

Diagnostic Aids

Important

Never solder the HO2S wires. For proper wire and connector repair refer to Wiring Repairs in Electrical Diagnosis.

Using the scan tool, observe the L.T. fuel trim values at the different RPM and the air flow conditions. The scan tool also displays the fuel trim cells, so the L.T. fuel trim values can be checked in each of the cells in order to determine when the DTC may have set. If the conditions for this DTC exist, the L.T. fuel trim values measure around 158 or greater.

Check for the following conditions:

A sensor pigtail may be mispositioned and contacting the exhaust manifold.
An intermittent ground in wire between the connector and the sensor.
A poor VCM ground.
Lean injectors: Perform the Injector Balance Test. Refer to Fuel Injector Balance Test for the 5.0L, 5.7L or the 7.4L.
Fuel Contamination: Water, even in small amounts, near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean exhaust and can also set this DTC.
Fuel pressure: If the pressure is too low, the system will be lean. In order to confirm, monitor a fuel pressure while driving the vehicle at various speeds and loads. Refer to Fuel System Diagnosis .
Exhaust leaks: If there is an exhaust leak, the engine may pull the outside air into the exhaust. and past the sensor.
Vacuum or the Crankcase leaks can cause a lean condition or a possibly a high idle.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

Running the engine at 1200 RPM keeps the HO2S temperature hot in order to ensure the HO2S remains active. Running the engine at 1200 RPM can indicate the exhaust oxygen content accurately.
Opening the HO2S circuit should result in a displayed voltage between 350 and 550 mV. If the display is still fixed below the 350 mV, the fault is a short to a ground in the HO2S high signal circuit or a faulty VCM.

Step

Action

Value(s)

Yes

No

1

Important

Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and the Failure Records for reference. This data will be lost when the clear DTC Information function is used.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Connect the scan tool.
Run the engine at the normal operating temperature.
Place the vehicle in park or neutral.
Apply the parking brake.
Increase the engine speed to the specified value.

Does the scan tool data display indicate a HO2S voltage fixed less than the specified value?

1200 RPM

5.0L - 0.086 V (86 mV)

5.7L - 0.026 V (26 mV)

7.4L - 0.017 V (17 mV)

Go to Step 3

Go to Step 4

3

Disconnect the HO2S.
Jumper the HO2S Low circuit to a ground.
Turn ON the ignition while leaving the engine OFF.

Does the scan tool data display indicate the HO2S voltage that is within the specified range.

0.35-0.55 V (350-550 mV)

Go to Step 7

Go to Step 5

4

The DTC is intermittent.

Are any additional DTCs stored?

--

Go to the applicable DTC table

Go to Diagnostic Aids

5

Check for a short to ground in the HO2S Signal circuit.

Was a problem found?

--

Go to Step 6

Go to Step 9

6

Repair the circuit as necessary. Refer to Wiring Repairs in Electrical Diagnosis.

Is the action complete?

--

Go to Step 10

--

7

Refer to Diagnostic Aids.

Was a problem found and repaired?

--

Go to Step 10

Go to Step 8

8

Replace the HO2S. Refer to Heated Oxygen Sensor (HO2S) Replacement .

Is the action complete?

--

Go to Step 10

--

9

Replace the VCM.

Important

When replacing the VCM, the new VCM will need to be programmed. Refer to VCM Replacement/Programming .

Is the action complete?

--

Go to Step 10

--

10

Use the scan tool in order to select the DTC and the Clear DTC Information functions.
Start the Engine.
Allow the engine to idle until the normal operating temperature is reached.
Select the DTC and the Specific DTC functions.
Enter the DTC number which was set.
Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic ran and passed?

--

Go to Step 11

Go to Step 2

11

Use the scan tool in order to display the Capture Info and the Review Capture Info functions.

Are there any DTCs displayed that have not been diagnosed?

--

Go to the applicable DTC table

System OK

For Error Code P0300, that is coming back as a misfire in the engine, here is more reading info on that subject:

Subject:SES Light and P0300 When Towing , Cruising Uphill or on Hard Acceleration - kw 4.3 5.0 5.7 accelerate cruise cylinderhead DTC L30 L31 L35 LF6 LU3 P0300 P0301 P0302 P0303 P0304 P0305 P0306 P0307 P0308 #PIP3081 - (07/23/2004)

Models:.

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Condition/Concern:

The vehicle may exhibit a SES Light due to a P0300 and misfire. If the misfire is related to the information below, it will typically happen while cruising uphill, pulling a trailer or on hard acceleration and then stop misfiring shortly after returning to an idle. Typically, cylinders 3,4,5 or 6 will be the ones to experience this.

Recommendation/Instructions:

If the P0300 SI diagnostics did not isolate a concern, the following may help:

Remove the valve cover, valve springs and valve seals on the effected cylinder or cylinders. A small wire tie or rubber bands can be placed in the valve stem keeper groove to prevent the valve from falling into the cylinder. Rotate the valve while moving it up and down in the guide to see if it binds. If a binding valve is found, remove both cylinder heads and use either of the following methods to increase the stem to guide clearance:

• Send the head out to a machine shop and advise them to increase the valve stem to guide clearance to 0.002 inch per guide.

• Hone the guide with a 9 mm hone, such as Snap On BCG249, until a clearance of 0.002 inch is obtained. This will usually take about 4 strokes of the hone.

Reassemble the cylinder heads using new valve seals.

.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

Models:

(96 - 02 Chevrolet Astro) and (96 - 02 GMC Safari) and (96 - 00 Old Body Style Chevrolet Suburban) and (96 - 00 Old Body Style Chevrolet Tahoe) and (96 - 02 Chevrolet Express) and (96 - 00 GMC Yukon) and (96 - 00 Chevrolet Old Body Style C/K Truck) and (96 - 00 GMC Old Body Style C/K Truck) and (96 -02 GMC Savana) and (96 - 99 P32 Cab and Chassis) and (96 - 02 Chevrolet S-10) and (99 - 02 Chevrolet Silverado with 4.3L V-6 Engines (96 - 02 GMC Sonoma) and (96 - 02 GMC Sierra with 4.3L V-6 Engines)

DTC P0300 Engine Misfire Detected

Circuit Description

The crankshaft position (CKP) sensor and the camshaft position (CMP) sensor are used in order to detect an engine misfire. The VCM monitors the speed of the crankshaft. The VCM detects a deceleration of the crankshaft that is not associated with a normal engine speed reduction. In order to determine if a misfire occurred, the VCM compares the deceleration information to the engine speed and the engine load. If a misfire event is determined, the VCM compares the crankshaft position to the cam sensor signal in order to determine which cylinder misfired. The VCM stores the information in separate accumulators for each cylinder. Upon completion (or failure) of the test, the VCM evaluates the number of misfires in each accumulator. If the accumulators are somewhat even or if 3 or more cylinders are misfiring, then this determines that a random misfire has occurred. The VCM also utilizes the input from the ABS wheel speed sensor in order to determine if a rough road condition exists which could cause a crankshaft acceleration and deceleration. If a rough road condition exists, the diagnostic will not run. This DTC is a type B DTC.

Conditions for Setting the DTC

25 cycles have elapsed since Transmission shift (automatic only)
No TP sensor DTCs
No MAF sensor DTCs
NoCamshaft Position sensor DTCs
No VS sensor DTCs
No Crankshaft Position sensor DTCs
The ECT is greater than or equal to -7°C. for the 5.0L, 5.7L
The ECT is between -6.75°C and 129°C. for the 7.4L
The engine speed between 600 RPM and 5600 RPM for the 5.0L, 5.7L
The engine speed between 300 RPM and 4900 RPM for the 7.4L
The system voltage between 9 volts and 16 volts
The positive throttle position change is less than 4.9% for 100 msec.
The negative throttle position change is less than 2.9% for 100 msec.

Action Taken When the DTC Sets

If the VCM determines that the engine misfire is significant enough to have a negative impact on emissions, the VCM turns ON the malfunction indicator lamp (MIL) after the misfire has been detected on 2 non-consecutive trips under the same operating conditions. If the misfire is severe enough that catalytic converter damage could result, the MIL flashes while the misfire is present.

Conditions for Clearing the MIL/DTC

The VCM turns OFF the MIL after 3 consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (the coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle) or the scan tool clearing feature has been used.

Diagnostic Aids

The Misfire Index counts the number of misfires. The scan tool can monitor the Misfire Index. There is a current and history misfire counter for each cylinder. Use the current misfire counter in order to determine which cylinder is misfiring.

Many different condition could cause an intermittent misfire.

Check for the following conditions:

Check the spark plug wires and the coil wire for the following conditions:
- Ensure that the spark plug wires are securely attached to the spark plugs and the distributor cap.

- Check the wire routing in order to ensure that crossfiring is not occurring.

- If the misfire occurs when the weather is damp, the problem could be due to worn plug wires. In order to test for this condition, spray the wires with water and with the engine running, watch for spark to jump from the wires. If a spark is visible, replace the wires.
Check for contaminated and a low fuel level and the following conditions:
- Check the fuel condition and quality. Dirty or contaminated fuel could cause a misfire condition.

- If the fuel level is low, contaminants in the bottom of the fuel tank could enter into the fuel metering system.

For more information, refer to fuel supply system.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

If DTCs P0337 (Crankshaft Position Sensor Circuit Low Input) or P0338 (Crankshaft Position Sensor Circuit - High Input) are set, this could result in a misfire condition.
In order to duplicate the conditions under which the misfire occurred, it may be necessary to drive the vehicle and monitor the scan tool DTC Set This Ignition Cycle variable.
When checking the spark at the spark plug wires, the spark should be consistent. A few sparks then nothing is no spark.
At this point, the ignition system is OK and the problem may be in the fuel system. Fuel System Diagnosis must be performed in order to determine the cause of the problem.

Step

Action

Value(s)

Yes

No

1

Important

Before clearing the DTCs use the scan tool to record freeze frame and failure records for reference, as data will be lost when Clear Info function is used.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Review Failure Records data.

Are there any other DTCs stored?

--

Go to Applicable DTC Table

Go to Step 3

3

Install a scan tool.
With engine idling, monitor the MAP sensor voltage on the scan tool.

Is the MAP sensor voltage greater than the specified value?

4.0V

Go to DTC P0108 Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage

Go to Step 4

4

Duplicate the conditions during which the misfire occurred.

Is the DTC active at the ignition cycle?

--

Go to Step 5

Go to Step 10

5

Using a scan tool, review the Misfire Index. Is the Misfire Index increasing for more than one cylinder?

--

Go to Diagnostic Aids

Go to Step 6

6

Install the spark plug tester J 26792 on number 1 spark plug wire.
Disconnect the fuel injector harness at the intake manifold.
Crank the engine, spark should jump the tester gap.
Repeat for each spark plug wire.

Was the spark adequate on all of the spark plug wires?

--

Go to Step 7

Go to Step 11

<a href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=65956&psdid=33&evc=sm#TD07">7

Inspect the spark plugs for wear, excessive air gaps, cracks, or fouling.

Are the spark plugs OK?

--

Go to Step 8

Go to Step 12

8

Perform a cylinder compression test. Refer to Engine Mechanical.

Was a problem found?

--

Go to Step 14

Go to Step 9

9

Refer to Fuel System Diagnosis

Is the fuel system OK?

--

Go to Step 10

Go to Step 13

10

Misfire is intermittent and is currently not active.

Go to the Diagnostic Aids.

--

11

Refer to Enhanced Ignition System .

--

12

Replace the spark plugs.

Is the action complete?

--

Go to Step 14

--

13

Make repairs as indicated by the Fuel System Diagnosis. Refer to Fuel System Diagnosis .

Is the action complete?

--

Go to Step 14

--

14

Using the scan tool, select the DTC and the Clear Info.
Start the engine.
Idle at the normal operating temperature.
Select the DTC and the Specific.
Enter the DTC number which was set.
Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic ran and passed?

--

Go to Step 15

Go to Step 2

15

Using the scan tool, select Capture Info and Review Info.

Are any DTCs displayed that have not been diagnosed?

--

Go to the Applicable DTC Table

System OK