P1000 – On Board Diagnostic System Readiness Test Not Complete (Ford)

By Reinier (Contact Me)
Last Updated 2018-03-20
Automobile Repair Shop Owner

Table of Contents

1. What Does Code P1000 Mean?
2. Where is the P1000 sensor located?
3. What are the common causes of code P1000?
4. Get Help with P1000

What Does Code P1000 Mean?

OBD II fault code P1000 is a manufacturer specific code that is defined by carmaker Ford as “OBDII Monitor Testing Not Complete”, and is set when the PCM (Powertrain Control Module) detects that the Powertrain has not run through a complete self-diagnostic cycle of all readiness monitors.

NOTE: Be aware that while carmakers Jaguar, Mazda, Lincoln, Mercury, Oldsmobile, Mercedes, and KIA also use code P1000 with the definition “OBDII Monitor Testing Not Complete”, this guide applies primarily to Ford applications.  

Emissions regulations require that all OBD II-equipped vehicles must be able to perform a series of self-diagnostic tests on all prescribed readiness monitors in order for the vehicle to be fully compliant with all emissions regulations. In simple terms, a readiness monitor can be thought of as a set of programming rules that is designed to test the operational status of a particular system that has the potential to increase exhaust emissions if that system does not operate as expected or designed.

In practice, readiness monitors come in two “flavors”; continuous, and non-continuous, and collectively, the readiness monitors ensure that every aspect of the engine and fuel management systems is tested by the PCM. This is a legal requirement to ensure that there are no malfunctions, defects, or faults present on the application that can cause the total volume of emissions produced by the vehicle to fall outside of legal limits.

Note however that the purpose of compulsory emissions testing is not only to measure the emissions produced by the application, but also to test the PCM’s ability to run and complete all prescribed readiness monitors successfully. Should the emissions test reveal the PCM’s ability to run any tests on any readiness monitor(s) for any reason, including tampering with PCM’s ability to run self-diagnostic tests, the application will fail the test.

Below is a rundown of the readiness monitors and some details of the systems each monitor relates to, starting with the continuous monitors, which include the-

– Comprehensive Component Monitor

The comprehensive component monitor runs continuously when the engine is running, and it checks the operation, performance, and rationality of all electronic systems and components that have the potential to effect emissions should they fail. Typical checks include checking for short circuits, open circuits, or driver circuit failures in coil packs, brake switches, transmission shift solenoids (during shifting) and crankshaft position sensors. Note that this monitor tests all components that are not checked by any other monitor.

– Misfire Detection Monitor

This monitor also runs continuously when the engine is running during normal engine operation, and its purpose is to determine if misfires are present that are releasing excessive volumes of harmful exhaust emissions. Since misfires create subtle changes in the rotational speed of the crankshaft, most applications detect misfires by monitoring the rotational speed of the crankshaft via the crankshaft position sensor. Depending on the cause of the misfire(s), the PCM may set code P0300 (Random Misfire Detected) or one or more codes that identify the misfiring cylinder(s).

– Fuel System Monitor

This monitor also runs continually during normal engine operation, and its purpose is to assess the ability of the fuel system to maintain the optimal air/fuel ratio throughout the engines’ operating range. Note however that this monitor takes into account the normal wear and tear that occurs on parts such as the fuel pump, idle air control system, throttle body (and others), as well as the loss of sensitivity that occurs in oxygen-, air/fuel ratio sensors after long use.

Non-Continuous Monitors

All other monitors only run at certain times and under predefined conditions. These sensors include the following-

– Oxygen (O2) Sensor Monitor

This monitor checks that the oxygen sensors are properly calibrated, and are functioning as expected during normal engine operation. “Functioning as expected,” means that the oxygen sensors are checked to verify that they enter closed-loop operation, which allows the PCM to use the input data from the oxygen sensors to make suitable and appropriate adjustments to the injector pulse width and other settings to maintain the air fuel mixture as close to 14.7: 1 as possible.

Typically, the monitor checks for proper voltage thresholds and response times to changing air/fuel mixture changes in the upstream oxygen sensors, and voltage thresholds and the ability to recognize lean conditions in downstream oxygen sensors.

– Oxygen Sensor Heater Monitor

All oxygen sensors use dedicated heater elements to speed up the sensors’ warm-up time and this monitor checks the operation, functionality, and rationality of all the sensor’s heating elements and their associated control/signal circuits. Note that on most applications, this monitor runs concurrently with the oxygen sensor monitor, which means that oxygen sensor heater monitor may not run, or may not complete if there are issues present that prevent the oxygen sensor monitor from running or completing successfully.

– Catalytic Converter Monitor

This monitor checks the catalytic converters’ ability to convert harmful exhaust emissions into less harmful substances. Note that for this monitor to run or complete successfully, the CHECK ENGINE light must not be illuminated, and both the oxygen sensor monitor, and the oxygen sensor heater element monitor must have completed successfully. Note also that the efficiency of the catalytic converter must have been above 50% during the previous drive cycle for this monitor to complete successfully.

– EGR System Monitor

Note that this monitor is only present on applications that use an EGR (Exhaust Gas Recirculation) system as a means to limit the formation of oxides of nitrogen (NOx) during the combustion process. On these applications, a small volume of exhaust gas is introduced into the cylinders, which has a quenching effect on combustion temperatures, which in turn, limits or prevents the formation of NOx during combustion. Since the introduction of exhaust gas into the engine affects combustion, this monitor is used both to verify that there is no EGR flow at idle, and that the proper volume of exhaust gas flows through the system when the PCM commands the EGR valve open when operating conditions allow the introduction of exhaust gas into the engine.

– EVAP System Monitor

This monitor tests the EVAP (Evaporative Emissions) systems’ ability to capture, store, and convey fuel vapors to the engine to be combusted along with the primary air/fuel mixture. Depending on the system design, the monitor may apply either a vacuum or a positive pressure to test the system for the presence of leaks through which fuel vapors can escape into the atmosphere. Note also that all EVAP monitors are able to differentiate between small leaks of up to.020 inches in diameter, and large leaks that are typically up to, and larger than, .040 inches in diameter.

–  Secondary AIR System Monitor

Some applications use a secondary air injection system to blow excess atmospheric air through the exhaust system to help speed up the heating of the catalytic converter when the ambient temperature is at, or below a predefined limit when a cold engine is first started. Therefore, the monitor checks the entire secondary air injection system for voltage thresholds and signal rationality to ensure that the system is functioning as expected. Note that for this monitor to run, the CHECK ENGINE light must be off, and the oxygen sensor monitor, as well as all continuous monitors must have run and completed successfully.

Where is the P1000 sensor located?

The image above shows some of the parts, components, and systems whose integrity/ functionality are subject to verification by a readiness monitor. Note though that the actual location of a system or component that fails verification by any given monitor depends both on the application, and the monitor that did the actual testing. Therefore, it is important to refer to the manual for the affected application for details on readiness monitors, as well as details on the most likely causes that can prevent monitors to run or complete on that application to avoid confusion, misdiagnoses, and the unnecessary replacement or parts and/or components.

What are the common causes of code P1000?

NOTE : Note that in cases where an underlying fault is preventing the PCM from running self-diagnostic tests, one or more additional codes relating to the underlying fault will be stored as well, either as an active code, or as a pending code if no warning lights are illuminated.

Nonetheless, the possible causes of code P1000 are many and varied, but could include the following-

• Erasing of all stored fault codes, and failing to complete a drive cycle afterwards
• Disconnecting the battery, and failing to complete a full drive cycle after reconnecting the battery
• Failure to complete a full drive cycle after reprogramming the PCM during a repair procedure
• Failure to complete a full drive cycle after programming the PCM, such as might be the case when a new vehicle leaves the factory or assembly plant
• The presence of any fault code that prevents all the enabling conditions of a particular monitor to be met
• The absence of any enabling condition, for instance, the fuel tank is not between 25% and 75% full, which will prevent the EVAP monitor from running or completing successfully.

WARNING:  Readiness monitors have very specific enabling conditions that MUST be met before that monitor will run or complete. In fact, some monitors require that one or more other monitors run and complete before they will themselves run or complete. Thus, from a diagnostic point of view, and particularly when additional codes are present, it is important to gain at least a basic understanding of which monitors are present on the affected application, what their enabling conditions are, and most importantly, the nature of the relationship(s) between monitors that depend on each other to run or complete.

However, it must be noted that if no additional codes are present, code P1000 can almost always be “cleared” simply by completing at least one full drive cycle, but note that this drive cycle MUST be completed EXACTLY as prescribed in the affected application’s manual.    

NOTE: Note that code P1000 is also used by car maker GM, who defines this code as “Ignition Circuit Low”.

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