What P2104 means
The ECU has detected a fault severe enough that it forces the throttle actuator to the idle stop.
How the engine computer detects it
The driver loses pedal authority — only idle is available until the underlying TAC fault clears.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Check engine light on
- Reduced throttle response, possible limp mode
- Hesitation or surging
- Idle too high or too low
Common causes
- Severe upstream TAC fault Most likely
- Throttle position signal invalid Possible
How to diagnose P2104
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: throttle actuator control, ecm.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Vehicles that report P2104 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Ford F-150 | 2005–2008 | 6 | 61k | |
| Ford Fusion | 2008–2011 | 6 | 110k | |
| Ford Freestyle | 2005–2007 | 4 | 140k | |
| Ford Expedition | 2005 | 3 | 85k | |
| Ford Explorer | 2004–2006 | 3 | 78k | |
| Ford 500 | 2005–2006 | 3 | 160k |
Counts of owner complaints to the NHTSA that mention P2104 (31 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 2
- Generic (SAE) code
- 104
- Specific fault
Questions drivers ask
Can I drive with code P2104?
Drive gently and only as far as you need to. The engine computer may limit power to protect the engine, so avoid highways and heavy traffic until it's fixed. If the check engine light starts flashing, pull over.
Will my car pass an emissions inspection with P2104?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Will P2104 clear by itself?
The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.
Often reported together
Codes that owners mention in the same NHTSA complaints as P2104. They can point to a shared cause, so it's worth checking them together.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.