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Mode 07: pending codes and catching a fault before the lamp
A fault detected once, not yet confirmed, and not yet worth a warning lamp. Reading these is how you find problems while they are still cheap.
Most emissions faults must be detected on two consecutive drive cycles before the warning lamp illuminates. The reason is straightforward: a single anomalous reading should not send a driver to a workshop.
But the ECU records that first detection, and Mode 07 is how you read it.
Related: pending vs stored codes and two-trip logic and MIL illumination.
Where a pending code sits
| Stage | What it means |
|---|---|
| Nothing | No fault detected |
| Pending (Mode 07) | Detected once, awaiting confirmation |
| Stored/confirmed (Mode 03) | Detected on a second cycle — lamp on |
| Permanent (Mode 0A) | Confirmed, and not clearable until verified fixed: Mode 0A permanent DTCs |
A pending code is a fault that has happened. It is not a false alarm. It is a fault that has not yet happened twice.
The three reasons to read them
1. Early warning
An intermittent misfire, a marginal sensor, an EVAP leak that only shows in certain conditions — all appear here before the lamp comes on.
Acting at that stage is cheaper. A misfire caught pending is a coil; a misfire caught after weeks of driving can include a catalytic converter: P0420 catalyst code explained.
2. Verifying a repair
After a repair, cleared codes and no lamp is not proof. A pending code appearing during the verification drive means the fault is still occurring — you just have not driven far enough for it to be confirmed.
Check Mode 07 during the drive after any repair: post-repair verification OBD checklist.
3. Chasing intermittents
An intermittent fault that never quite confirms may still leave pending codes repeatedly. Reading them regularly catches what a single scan misses.
Diagnosing intermittent faults with OBD.
What not to do with them
Do not clear them reflexively. A pending code is free information about something that happened. Clearing it removes the record and the freeze frame that came with it.
Do not panic about a single one either. A pending code after refuelling, after a very cold start, or after driving through deep water may not repeat.
The right response is to note it, note the conditions, and check again after a few days of normal driving.
Clearing codes: when and why and driving through flood water.
Reading them on a used car
Combined with stored, permanent and readiness data, pending codes complete the picture:
| Finding | Interpretation |
|---|---|
| Nothing anywhere, monitors complete | Genuinely clean |
| Pending codes only | A fault is developing |
| No stored codes, monitors not ready | Cleared recently |
| Permanent codes stored | Cleared recently, and here is what for |
A car with pending codes and no lamp is a car with a problem the seller may not know about — which is a better negotiating position than a car with a lamp.
Used car pre-purchase OBD check and OBD readiness monitors explained.
Which faults skip the two-trip rule
Not everything waits.
Misfires severe enough to damage the catalyst illuminate the lamp immediately, and make it flash. That is a stop-driving warning, not a pending code: check engine blinking vs solid.
Fuel system and misfire faults generally have faster confirmation logic than EVAP or catalyst faults, which are slow by design.
Making it a habit
The most useful thing about Mode 07 is that it costs nothing to check.
A scan once a month — stored, pending, permanent, readiness — takes two minutes and finds developing problems while they are still small.
How often to do car diagnostics and the first OBD scan after buying a used car.
Try it on the free tier of the app — pair an ELM327 adapter and read pending codes alongside stored ones every time you scan. The pending list is where next month’s problem is written down today.
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