P0000 Code: No Trouble Code Stored (P0000)
P0000 is not a fault: the scanner found no stored code. It is a placeholder that means the memory is empty.
At a glance
Severity: Minor
- Meaning
- No Trouble Code Stored (P0000)
- System
- ECU & Outputs · Powertrain
- Safe to drive?
- Yes, short term
- Typical repair cost
- $0–$500
- DIY difficulty
- Very easy
P0000 is the code number the standard reserves for no trouble code at all, so seeing it on a scanner means the engine computer answered and reported an empty fault memory for the mode that was read. Many apps and cheap Bluetooth adapters print P0000 instead of a friendly no codes found message, and some show it when the read failed halfway. The confusing part is when the check engine light is still on: the lamp may be a different warning light, the fault may sit in the pending or permanent list the tool didn't read, or it may be a manufacturer code that a basic generic reader can't see. P0000 on its own never needs a repair, but it is worth confirming that the scan was complete before you trust it.
Can I keep driving? If the check engine light is off and the car drives normally, there is nothing to fix. If a light is on or the engine behaves oddly, drive normally but get a full scan with a better tool before assuming the car is healthy.
Try this first – 5-minute fix
- Re-scan with the engine running Start the engine, wait for the idle to settle and read again. Some adapters only connect reliably with the engine running, and a genuine read also shows live rpm.
- Look at pending codes and MIL status Open the pending codes list and the monitor or status screen. If the MIL is commanded off and nothing is pending, the result is a real all-clear.
- Check the gas cap and wait a few trips If the light came on after refueling and a later scan is empty, tighten the cap until it clicks. An intermittent evap fault often turns the light off by itself after three clean trips.
How to read P0000
- P Powertrain
- 0 Generic (SAE)
- 0 Fuel/air & emissions (aux.)
- 00 Specific fault
Symptoms
- Scanner or phone app lists P0000 or shows an empty code list
- Check engine light still on, blinking or coming on only now and then
- An amber light with a wrench, a Maint Reqd or Service reminder on the dash while the scanner shows nothing
- Emissions test rejection for not-ready monitors even though no code is stored
- Car runs fine and no warning light: the P0000 result is simply a clean bill
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- The fault healed or was cleared: the lamp went out after several good trips, or someone cleared codes, leaving nothing to report
- The dash light isn't the check engine lamp at all but a maintenance reminder or another system's warning
- The tool only read confirmed codes; the problem is a pending code, or a manufacturer code in the engine or transmission module
- Adapter or app shows P0000 as a placeholder because the connection dropped or the protocol wasn't recognized
- A permanent code is stored that clears only after the monitor re-runs, and the reader can't display that list
- Fault in the lamp circuit, instrument cluster or engine computer that keeps the light on without a code
Diagnosis step by step
Identify the light
Check the owner's manual for the exact symbol. The check engine light is an engine outline, usually amber. A wrench, oil can, Maint Reqd text or a coil symbol on a diesel are different lamps with different reasons, and none of them will show up as an engine code.
Tools: Flashlight
Read the MIL status and code count
Most scanners show a status screen (Mode 01, PID 01) with the MIL commanded on or off and how many codes are stored. MIL commanded on with zero codes shown means your tool is missing something; MIL off with zero codes means the computer is genuinely clean.
Tools: OBD-II scanner
Read pending and permanent codes
Pending codes (Mode 07) are faults seen once but not yet confirmed; permanent codes (Mode 0A) survive a clear and only disappear after the self-test passes. Many budget readers only show stored codes, so switch to a tool that lists all three categories.
Tools: OBD-II scanner
Check the readiness monitors
Look at the monitor list: catalyst, evap, O2 sensor, O2 heater, EGR or secondary air. After a battery disconnect or a code clear, several will read incomplete for 50 to 150 miles of mixed driving. That is the usual reason a car with P0000 is still turned away at a smog check.
Tools: OBD-II scanner
Scan every module with an enhanced tool
A generic reader talks only to the emissions part of the engine computer. A shop tool or an enhanced app can read manufacturer codes in the engine, transmission, ABS and body modules. On some cars the transmission module asks the engine computer to light the MIL, and a generic tool just sees P0700 or nothing.
Tools: OBD-II scanner
Rule out connection problems
If the tool shows P0000 but also no live data such as rpm or coolant temperature, the link isn't working. Check that pin 16 of the diagnostic connector has battery power (it often shares the accessory or cigarette lighter fuse), try with the engine running, and try a second tool.
Tools: Multimeter, OBD-II scanner
Where the parts are
- 1Ignition coil
- 2Spark plug
- 3Fuel injector
- 4Camshaft sensor
- 5Crankshaft sensor
- 6Engine computer (ECM)
- 7Intake manifold
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| No repair needed: scan confirms empty memory and MIL off | Yes | $0 |
| Full-system scan with a professional tool | No | $0–$150 |
| Drive cycle to complete readiness monitors before a test | Yes | $0–$100 |
| Restore power or ground at the diagnostic connector (fuse, pin repair) | Yes | $5–$150 |
| Diagnose MIL circuit, instrument cluster or engine computer | No | $100–$500 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Honda
Honda's amber wrench and Maint Minder codes such as A1 or B12 are service reminders, not engine faults. They reset through the instrument panel menu and never appear on an OBD scanner, so a P0000 result is expected.
Toyota
Many Toyota models show a MAINT REQD light every 5,000 miles. It is an oil-change reminder reset through the trip meter or the settings menu, and it has nothing to do with the check engine light.
Emissions / smog test impact
Depends
A P0000 read with the MIL off passes the code part of an OBD smog check, but the test also looks at readiness monitors. Most states allow only one incomplete monitor on newer cars (two on older ones), so after a code clear or a battery change drive for a few days before you go.
Frequently asked questions
Is P0000 a real fault code?
No. The number is reserved to mean no fault, and some tools display it instead of a text message. Nothing on the car is broken because of it.
My check engine light is on but the scanner says P0000. Why?
The most common reasons are a pending or manufacturer-specific code the reader didn't request, a code stored in the transmission module, or a bad connection. Check the MIL status screen: if it says the MIL is commanded on, a full scan with a better tool will find the reason.
The light was on yesterday and today the scan shows P0000. What happened?
Many faults, especially evap leaks and one-off misfires, turn the lamp off after three drive cycles without the fault. The history code may still be in memory for a while, but some readers don't show it. If it keeps coming back, get it diagnosed while it is active.
Will I pass the emissions test with P0000?
Only if the check engine light is off and enough readiness monitors are complete. Clearing codes right before the test resets the monitors, and the station will reject the car as not ready even though it shows no codes.