P25B7 code meaning
Auxiliary Ignition Switch On/Start Position Circuit
What P25B7 means
P25B7 covers the hard-wired input from an auxiliary ignition switch that commands the On and Start positions from a second location, for example a rear panel behind the cab, a work platform or a remote station on a chassis-cab truck. The module flags a state on this line it cannot interpret, such as an open circuit, without saying whether the level is too low or too high. No manufacturer documents P25B7 publicly. The nearest published logic is the main run/crank input, for which the GM brake control module in table 25OBDG04A sets P2534 when its wake-up line stays low for 3 s while the ECM reports run or crank. Navistar describes remote start and shutdown panels for PTO bodies built on this principle. For the driver, the remote start point may stop responding while the key in the cab still works.
P25B7 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P25B7
- Engine cannot be started or switched on from the auxiliary position
- Normal key or push-button start still works
- Stored code, often without other complaints
Common causes of P25B7
- Most likelyOpen wire or loose connector in the harness to the body or remote panel
- PossibleWorn or corroded contacts in the auxiliary switch
- PossibleFaulty or modified upfitter wiring
- Less likelyInput stage of the reading module damaged
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Auxiliary ignition switchWiring harness
What each part of P25B7 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| B7 | The exact fault in that area. |
What to do next
- Note P25B7 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P25B7
What does P25B7 mean?
P25B7 means "Auxiliary Ignition Switch On/Start Position Circuit". P25B7 covers the hard-wired input from an auxiliary ignition switch that commands the On and Start positions from a second location, for example a rear panel behind the cab, a work platform or a remote station on a chassis-cab truck. It is a generic code, so it means the same on every make.
Is it safe to drive with P25B7?
P25B7 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P25B7 fail an emissions test?
P25B7 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P25B7 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will P25B7 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.