P1000: OBD Systems Readiness Test Not Complete
Key takeaways
- On Ford, Mazda and Jaguar vehicles, P1000 means the engine computer hasn't finished all its emissions self-tests yet; it is not a fault.
- It shows up after the battery was disconnected or replaced, the codes were cleared, or the engine computer was reprogrammed.
- It's safe to drive; P1000 clears on its own once a full drive cycle lets every monitor complete, usually within a few days to a week of mixed driving.
- The catch is emissions testing: a car with incomplete monitors can be turned away, so wait for P1000 to clear before an inspection.
- On other makes P1000 can mean something different; heavy-truck bulletins use it for unrelated conditions.
What P1000 means
Your car’s computer hasn’t finished checking itself yet, and nothing is wrong. On Ford, Lincoln, Mercury, Mazda and Jaguar vehicles, P1000 means “OBD Systems Readiness Test Not Complete.” The engine computer runs a set of emissions self-tests, called readiness monitors, for the catalytic converter, oxygen sensors, evaporative (EVAP) system, misfire, fuel system and others. Until every one of them has run at least once since the computer’s memory was last erased, it keeps P1000 stored as a reminder.
P1000 is a manufacturer-specific code, so its meaning depends on the make. On other brands it can mean something unrelated, and heavy-truck makers use it for their own conditions. Check the make before you read too much into it.
Is it safe to drive?
Yes. P1000 by itself is not a fault, it doesn’t affect how the car runs, and in fact driving is the only thing that clears it.
What changes the answer is anything else. If the check engine light is on, it’s flashing, or the car runs rough, P1000 isn’t the reason: there’s another code stored, and that one decides whether you should drive. Read all codes, not just the first one, and see check engine light on for what to do next.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Battery disconnected, replaced or run flat | Recent battery work, jump start or a dead battery | $0; drive normally |
| Codes cleared with a scan tool | Someone cleared a check engine light recently | $0; drive normally |
| Engine computer reprogrammed or replaced | Recent software update or module work at a shop | $0; drive normally |
| Only short trips, so the slower monitors never run | Scanner shows the same one or two monitors “not ready” for weeks | $0; plan a longer mixed drive |
| A fault stopping a monitor from running | Another code stored, or one monitor never completes after two weeks of mixed driving | $100–$180 diagnosis, plus the repair |
What to check first
- Read every stored code. If P1000 is alone, there’s nothing to fix. If there are others, deal with those first. Our guide to reading check engine light codes shows how.
- Think about what happened recently. A battery change, a jump start, a shop visit or a cleared code explains P1000 almost every time.
- Drive a full drive cycle. Start cold, idle a minute or two, drive some stop-and-go, then hold a steady 40–60 mph for several minutes, and repeat over a few days. Keep the fuel tank between a quarter and three-quarters full for the EVAP monitor.
- Don’t clear it. Clearing P1000 resets every monitor to “not ready” and starts the wait again. Our guide on how to reset the check engine light explains why any clear does this.
- Check the readiness screen before an emissions test. Most scanners show each monitor as ready or not ready.
NHTSA’s complaint database holds only 4 owner complaints mentioning P1000, and the only 2 manufacturer bulletins naming it come from Mack heavy trucks, where it means something else. That fits a code that marks a normal state, not a defect.
What it costs
The cheap and by far the most common outcome is $0: drive for a few days and P1000 goes away. If one monitor refuses to complete after a couple of weeks of mixed driving, a $100–$180 diagnosis finds out which one and why. The expensive outcome is whatever repair that turns up, and it would show as its own code.
Related codes
P1000 often hangs around longest after EVAP codes like P0455 and P0456 are cleared, because the EVAP monitor needs the most specific conditions to run. After a catalytic converter repair for P0420, the catalyst monitor also has to finish before P1000 clears.
What owners report to NHTSA
4 complaints filed with NHTSA mention P1000, 2 of them since 2015, across 4 different models. The component owners most often filed it under: power train.
Manufacturer service bulletins that name P1000
2 technical service bulletins and manufacturer communications filed with NHTSA mention P1000, from 1 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- MACK TD, bulletin 10215325: Mack Chassis - DTC P1000 - 00 Active On Diagnostic Trouble Code ( DTC ) Readout/Report, No Description or Diagnostic Information
- MACK MACK, bulletin 10126937: DTC P1000-00 may come active on a chassis, either alone or accompanying other SCR system codes.
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
How do I clear P1000?
Drive the car. P1000 goes away by itself once all the readiness monitors have run and passed. Clearing it with a scanner just starts the count over. A mix of a cold start, some steady highway driving and some stop-and-go over a few days usually does it.
Will P1000 make me fail an emissions test?
It can. Inspection stations check whether the readiness monitors are complete, and P1000 means at least one isn't. Most programs allow one incomplete monitor on 2001 and newer cars, but some monitors take longer than others, so wait until P1000 is gone.
Does P1000 turn on the check engine light?
Not on its own. It's an informational code you see when you plug in a scanner. If the check engine light is on, there's another code stored, and that code is the one to look up.
Why won't P1000 go away?
Usually because the car only makes short trips, so the longer monitors never get a chance to run. The evaporative system monitor also needs a cold start and a fuel tank between about a quarter and three-quarters full. If it's still there after a couple of weeks of mixed driving, a shop can check which monitor won't finish and why.
References
- New York DMV — What Do You Mean My Car's Not Ready? (OBD II readiness monitors and inspection)
- 40 CFR 86.1806-17: Onboard diagnostics requirements
- NHTSA Office of Defects Investigation — vehicle owner complaint flat files
- NHTSA Office of Defects Investigation — manufacturer communications (service bulletin) flat files