P1400

[Sir ffeJ]

So we just finished paying off our truck and she through her first CEL. P1400 is the code and the shop says it means a tune up.

Where would you guys start? I cleaned the TB about 3 years ago. Haven't changed the plugs or coil packs since she was born. She is sitting around 75,000 miles.

I don't want to just through parts at it. Where would you start?

 

[khill]

Wow, yeah, those plugs are due for a change in my opinion. I do mine every 50k as a minimum (maximum?).

As for the P1400, I'd look at the O2 sensor on the manifold. P1400 is related to the temperature of the exhaust not being what is expected. Ever changed those O2 sensors since you got the truck? If not, those are definitely due for a change too...

 

[Mounce]

Its nice to change plugs early but they're rated for 100k. Js. But, it wouldn't hurt to change them. Our plugs have 102k on them and still runs strong. It's my moms and she doesn't seem to believe in preventative maintenance, so they'll be they're until they burn out I guess lol.

 

[signalnc]

I would clean the throttle body once a year.that may solve your code issue.... ...what about the air cleaner, fuel filter?

 

[IllogicTC]

DTC P1400
Diagnostic Instructions
• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor
DTC P1400: Cold Start Emission Reduction Control System


Circuit/System Description
The catalytic converter must be warmed to efficiently reduce the emissions. The cold start strategy is to reduce the amount of time it takes to warm the catalytic converter. During a cold start, the engine idle speed is elevated and spark timing is retarded to allow the catalyst to warm quickly. This diagnostic monitors the following to build an exhaust energy model:

• Engine speed

• Spark advance

• Throttle position

• Engine airflow

• Engine coolant temperature

• Engine runtime

• Park/neutral position

• Vehicle speed

The actual model is then compared to the expected exhaust energy model.

Conditions for Running the DTC
• A cold start has been detected.

• The vehicle speed is less than 2 km/h.

• The engine is at idle with no input from the accelerator pedal.

• The airflow per cylinder is greater than 80 mg/cylinder.

• DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0220, P0222, P0223, P0201, P0202, P0203, P0204, P0205, P0206, P0300, P0335, P0336, P0351, P0352, P0353, P0354, P0355, P0356, P0502, P0506, P0507, P0601, P0602, P0603, P0604, P0606, P0607, P062F, P0641, P0651, P1101, P1516, P1682, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138, P2176, P2610 are not set.

• This DTC runs for 15 seconds within the first 70 seconds of start up. This diagnostic runs once per trip when a cold start has been determined.

Conditions for Setting the DTC
The actual exhaust energy model does not match the expected exhaust energy model.

Action Taken When the DTC Sets
• The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.

• The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/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
Any loading of the engine that lowers engine RPM, such as with partial application of the clutch, during the first 70 seconds of engine run time may set this DTC.

Circuit/System Verification
Allow the engine to cool. Monitor the Cold Startup parameter. This should indicate Yes. Start and idle the engine for at least 2 minutes. DTC P1400 should run and pass.

Circuit/System Testing
• Inspect the air intake system for the following:

- If any other DTCs are set, diagnose them first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

- Modified, damaged, or restricted

- Dirty or deteriorating air filter element

- Crankcase ventilation system for correct operation--Refer to Crankcase Ventilation System Inspection/Description .

- Water intrusion

- Vacuum leak and other un-metered air downstream of the mass air flow (MAF) sensor

- Intake manifold leak

• Inspect the exhaust system for the following:

- Water intrusion

- Exhaust leak

- Damaged, restricted, modified or enhanced exhaust system--Refer to Symptoms - Engine Exhaust .


This is the thing someone copy-pasted from a service manual to the OS, which I then copy-pasted here after stripping out about 20 ad links automatically embedded by Vertical Scope.

 

[Sir ffeJ]

Thanks for the feedback guys :thumb:

I had a look at the MAF last night and it looks as clean as the day it was put in. I removed a coil pack and looked at the plug, again it was really clean looking. I also had a peek at the TB and it does look dirty behind the butterfly.

I think I'll start with cleaning the TB first and see if that is the culprit. I realized after looking at the O2 sensor, I'm going to need the socket for it, if I go with changing that.

My wife also tells me last night on her way home from work, the CEL was not on. Hmmmm

 

[signalnc]

after you clean the TB, make sure you do the "relearn". I had all kinds of issues the first time i cleaned mine and didn't relearn.

 

[808_LS_EXT]

after you clean the TB, make sure you do the "relearn". I had all kinds of issues the first time i cleaned mine and didn't relearn.

Hey signalnc,
What is this re-learn procedure you speak of?

I bought a 2004, 4.2L I6 Ranier.

Ran great, except the engine would die (not idle) when the A/C was switched on.

I pulled/cleaned the throttle body... it was thick and grimey.
That fixed the A/C idle problem,
but now, I have a P0222 code, and Reduced Power (Light-On) situation.
The throttle has no response if I am pressing the brake pedal.
The Ranier will barely make it up my driveway under this reduced-power condition.

I swapped Throttle-Body with my Trailblazer...
No change in condition,,, which means the throttle body is not bad.

Something "blew" when R&R'd the throttle body.
The negative battery cable was off throughout the whole process.

Re-learn?
Thanks!

 

[Mounce]

Relearn consists of just letting it idle for a while without touching the gas.

Unsure of what p0222 is but check the wires on the TB harness, you might have pulled one of them out when removing the harness.

 

[808_LS_EXT]

Relearn consists of just letting it idle for a while without touching the gas.

Unsure of what p0222 is but check the wires on the TB harness, you might have pulled one of them out when removing the harness.

Thanks Mounce...

P0222= Throttle/Pedal Position Sensor/Switch "B" Circuit Low Input.

I've checked all pins on TB and slots in connector... all looks good.

 

[808_LS_EXT]

................ you might have pulled one of them out when removing the harness.

Yupp, you called it....

However, it didn't make itself obvious until I went to check for voltage in the connector slot.
When there was no voltage in the slot, I tugged on the wire and it popped out of the connector.
Stuffed (lack of a better term) the wire back in, and the wire now makes contact with the crimped connector in the slot.

BTW, once all the wires were connected, no relearn was required on either vehicle... just reconnect the battery and the Tbody functions flawlessly.

 

[Mounce]

I, myself, have never done the relearn and I've cleaned the TB twice. No issues.