OBD2 Monitors showing "not ready"

Tiny
PETE3323
  • FORD MUSTANG

My '98 Mustang Cobra with 4.6L and 90K miles needs a smog test. It has failed due to the fact that 3 of the test monitors show "not ready". Is there a quick way to make the monitors "ready"? I am now driving without proper tags until I can resolve this.
The car runs fine and there are no dtc's.

Please HELP! Thank you.

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Sunday, March 11th, 2007 AT 10:08 PM

12 Replies

Tiny
MIKEYBDMAN
  • MEMBER

I was under the impression that the P1391 was for a CMP Sensor Bank 2 Short To Ground. Are you having any running problems? A miss or something?

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Wednesday, January 3rd, 2007 AT 3:14 PM
Tiny
RYAGUDELO
  • MEMBER

This is in Addendum to my question which was diagnosed by a Mechanic P1391on my 1997Acura SLX with 138,000 miles, and the engine check continously appeared. There is no running problem or a miss or something. The mechanic gave me a wrong interpretation of the code to complicate the problem of my car. The car runs okey and there is no problem except the check engine light with the said code. I have a suspicion that the car is giving a false reading? What should be done? Would there be parts to change, like changing the O2 sensor? Is there a mass airflow problem causing a false reading? How much man hour labor cost?

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Wednesday, January 3rd, 2007 AT 3:29 PM
Tiny
MIKEYBDMAN
  • MEMBER

I understand why he kind of miss lead you. The code P1391 is not listed for your vehicle. If you have a chiltons manual, it should list the way to read the engine code without a scan tool. You basically just connect the Service Check Connector and that will make your Service engine soon light blink. Count the number of blinks in each cycle and refer to your manual as to what it is faulting. Most likey it is going to fault your Crankshaft sensor assembly. But I would try and verify that is your problem before spending the time and money replacing it.

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Wednesday, January 3rd, 2007 AT 4:10 PM
Tiny
RYAGUDELO
  • MEMBER

Hi! This is an Adendum question that I would like to know. Where is the Service Check Connector in my car Acura 1997 SLX? Secondly, what is Manufacturer Control Ignition System's misfire? In a situation of misfire, what should be done?

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Friday, January 5th, 2007 AT 6:08 PM
Tiny
LOSTINMARS
  • MEMBER

That code is for the "G" sensor. It works when the vehicle is in 4wd to sense deceleration. I'm pretty sure its located under the center console.

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Wednesday, January 10th, 2007 AT 5:10 PM
Tiny
TAURUSWHEEL
  • MEMBER

Are there any codes showing up? Has there been any reset of the system lately? There is a drive cycle that will allow the monitors to prove out, I'm not sure exactly, for your car, what it is. Hopefully someone on here can post the procedure for you

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Monday, March 12th, 2007 AT 2:16 PM
Tiny
PETE3323
  • MEMBER

I have already tried the ford drive cycle. I live in L.A. And it's nearly impossible to complete the way they instruct you to drive with the traffic out here. I was wondering if there is an easier way to get the monitors ready. There are no codes at all. I did use a predator programmer to tune the car and put the original tune back in for the emissions test. I realize that is the reason the "not ready's" are there. But how the heck can I get them back to normal?

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Monday, March 12th, 2007 AT 6:45 PM
Tiny
TAURUSWHEEL
  • MEMBER

If you have access to the emission control info for your car, look up the three monitors you're missing and see what specifically they require to run, did you modify the car in any way? Is that what a predator programmer is for?

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Monday, March 12th, 2007 AT 7:50 PM
Tiny
PETE3323
  • MEMBER

Yes, the predator modifies certain parameters for performance gains, however, it keeps the original tune which I have reinstalled. There are some modifications but they are very minor and should not affect these tests. Would the information on emmisions tests be in the owners manual?

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Monday, March 12th, 2007 AT 9:38 PM
Tiny
TAURUSWHEEL
  • MEMBER

I don't think so, you would probably have to consult an emissions diagnosis manual for your car, find the monitor tests, I would think itwould tell you what is needed to run the monitors. What are they? Which three?

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Monday, March 12th, 2007 AT 11:11 PM
Tiny
PETE3323
  • MEMBER

It's a '98 Mustang Cobra. The three monitors are 1. 2nd Air System 2. O2 sensor 3. O2 heater.

I don't have an emmisions manual. Can I get it on line?

Thanks so much for your help on this.

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Monday, March 12th, 2007 AT 11:15 PM
Tiny
TAURUSWHEEL
  • MEMBER

You can buy repair cd's on that big auction site for cheap, just for your year and model. Are numbers 2 and 3 the same sensor? I received a code about one of mine having a heater issue, turns out the sensor was broken: here's what I found: Secondary air monitor:
The Secondary Air Injection (AIR) System Monitor is an on-board strategy designed to monitor the proper function of the secondary air injection system. The AIR Monitor for the Electric Secondary Air Injection Pump system consists of two monitor circuits: an AIR circuit to diagnose concerns with the primary circuit side of the solid state relay (SSR), and an AIR Monitor circuit to diagnose concerns with the secondary circuit side of the SSR. A functional check is also performed that tests the ability of the AIR system to inject air into the exhaust. The functional check relies upon HO2S sensor feedback to determine the presence of air flow. The monitor is enabled during AIR system operation and only after certain base engine conditions are first satisfied. Input is required from the ECT, IAT, and CKP sensors and the HO2S Monitor test must also have passed without a fault detection to enable the AIR Monitor. The AIR Monitor is also activated during on demand self-test.

1. The AIR circuit is normally held high through the AIR bypass solenoid and SSR when the output driver is off. Therefore a low AIR circuit indicates a driver is always on and a high circuit indicates an open in the PCM.

The DTC associated with this test is DTC P0412.

2. The AIR Monitor circuit is held low by the resistance path through the AIR pump when the pump is off. If the AIR Monitor circuit is high there is either an open circuit to the PCM from the pump or there is power supplied to the AIR Pump. If the AIR Monitor is low when the pump is commanded on, there is either an open circuit from the SSR or the SSR has failed to supply power to the pump.

The DTCs associated with this test are DTCs P1413 and P1414.

3. The functional check may be done in two parts: at startup when the AIR pump is normally commanded on, or during a hot idle if the startup test was not able to be performed. The flow test relies upon the HO2S to detect the presence of additional air in the exhaust when introduced by the Secondary Air Injection system.

The DTC associated with this test is DTC P0411.

4. The MIL is activated after one of the above tests fail on two consecutive drive cycles.

O2 sensors;
The HO2S Monitor is an on-board strategy designed to monitor the HO2S sensors for a malfunction or deterioration which can affect emissions. The fuel control or upstream HO2S is checked for proper output voltage and response rate (the time it takes to switch from lean to rich and vice versa). Downstream HO2S used for Catalyst Monitor are also monitored for proper output voltage. The following illustration shows that input is required from the ECT, IAT, MAF and CKP sensors to activate the HO2S Monitor. The Fuel System Monitor and Misfire Detection Monitor must also have completed successfully before the HO2S Monitor is enabled.

1. The HO2S sensor senses the oxygen content in the exhaust flow and outputs a voltage between zero and 1.0 volt. Lean of stoichiometric (air/fuel ratio of approximately 14.7:1), the HO2S will generate a voltage between zero and 0.45 volt. Rich of stoichiometric, the HO2S will generate a voltage between 0.45 and 1.0 volt. The HO2S Monitor evaluates both the upstream (fuel control) and downstream (Catalyst Monitor) HO2S for proper function.

2. Once the HO2S Monitor is enabled, the upstream HO2S signal voltage amplitude and response frequency are checked. Excessive voltage is determined by comparing the HO2S signal voltage to a maximum calibratable threshold voltage. A fixed frequency closed loop fuel control routine is executed and the upstream HO2S voltage amplitude and output response frequency are observed. A sample of the upstream HO2S signal is evaluated to determine if the sensor is capable of switching or has a slow response rate. A HO2S heater circuit fault is determined by turning the heater on and off and looking for a corresponding change in the Output State Monitor (OSM) and by measuring the current going through the heater circuit. The HO2S Monitor DTCs can be categorized as follows:

The DTCs associated with HO2S lack of switching are DTCs P1130, P1131, P1132, P1150, P1151 and P1152.

The DTCs associated with HO2S slow response rate are DTCs P0133 and P0153.

The DTCs associated with HO2S signal circuit malfunction are DTCs P0131, P0136, P0151 and P0156.

The DTCs associated with a HO2S heater circuit malfunction are DTCs P0135, P0141, P0155 and P0161.

The DTC associated with the downstream HO2S not running in on-demand is DTC P1127.

The DTCs associated with swapped HO2S connectors are DTCs P1128 and P1129.

3. The MIL is activated after a fault is detected on two consecutive drive cycles.

Short overview of the obdII system:
Overview

The California Air Resources Board (CARB) began regulating On Board Diagnostic (OBD) systems for vehicles sold in California beginning with the 1988 model year. The initial requirements, known as OBD I, required identifying the likely area of malfunction with regard to the fuel metering system. The Exhaust Gas Recirculation (EGR) system, emission-related components and the Powertrain Control Module (PCM). A malfunction indicator lamp (MIL) labeled CHECK ENGINE or SERVICE ENGINE SOON was required to illuminate and alert the driver of the malfunction and the need to service the emission control system. A fault code or Diagnostic Trouble Code (DTC) was required to assist in identifying the system or component associated with the fault.

Starting with the 1994 model year, both CARB and Environmental Protection Agency (EPA) mandated enhanced OBD systems, commonly known as OBD-II. The objectives of the OBD-II system are to improve air quality by reducing high in-use emissions caused by emission-related malfunctions, reducing the time between the occurrence of a malfunction and its detection and repair, and assisting in the diagnosis and repair of emission-related problems. By the 1996 model year, all California passenger cars and trucks (up to 14,000 lb GVWR) and all federal passenger cars and trucks (up to 8,5000 lb GVWR) are required to comply with either CARB-OBD II or EPA OBD requirements. These requirements apply to gasoline vehicles, diesel vehicles and are being phased in on alternative-fuel vehicles as well.

The OBD II system monitors virtually all emission control systems and components that can affect tailpipe or evaporative emissions. In most cases, malfunctions must be detected before emissions exceed 1.5 times the applicable 50K- or 100K-mile emission standards. If a system or component exceeds emission thresholds or fails to operate within a manufacturer's specifications, a DTC will be stored and the MIL will be illuminated within two driving cycles.

The OBD II system monitors for malfunctions either continuously, regardless of driving mode, or non-continuously, once per drive cycle during specific drive modes. A DTC is stored in the PCM Keep Alive Memory (KAM) when a malfunction is initially detected. In most cases the MIL is illuminated after two consecutive drive cycles with the malfunction present. Once the MIL is illuminated, three consecutive drive cycles without a malfunction detected are required to extinguish the MIL. The DTC is erased after 40 engine warm-up cycles once the MIL is extinguished.

In addition to specifying and standardizing much of the diagnostics and MIL operation, OBD-II requires the use of a standard Diagnostic Link Connector (DLC), standard communication links and messages, standardized DTCs and terminology. Examples of standard diagnostic information are freeze frame data and Inspection Maintenance (IM) Readiness Indicators.

Freeze frame data describes data stored in KAM at the point the malfunction is initially detected. Freeze frame data consists of parameters such as engine rpm and load, state of fuel control, spark, and warm-up status. Freeze frame data is stored at the time the first malfunction is detected, however, previously stored conditions will be replaced if a fuel or misfire fault is detected. This data is accessible with the scan tool to assist in repairing the vehicle.

OBD II Inspection Maintenance (IM) Readiness indicators show whether all of the OBD II monitors have been completed since KAM was last cleared. Ford also stores a P1000 DTC to indicate that some monitors have not completed. In some states, it may be necessary to perform an OBD check in order to renew a vehicle registration. The IM Readiness indicators must show that all monitors have been completed prior to the OBD check.

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Tuesday, March 13th, 2007 AT 6:59 PM

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