P2801: Transmission Range Sensor B Circuit Range/Performance
What to do
Apply the parking brake every time you park, and treat the selector display with suspicion. The transmission has lost one of the two witnesses it uses to confirm which range it is in — check the car is truly holding before stepping away, and expect the occasional refused shift or reluctant start while it protects itself. Repair promptly; the second sensor is now the only one.
What this code means
Transmission range sensor B is reading outside its expected range.
Range/performance means the signal is present but implausible — a value between valid states, or movement no mechanism could produce. That points at partial corrosion or a drifting sensor rather than a clean break.
A second range sensor exists because the first one guarding park is not enough. The range sensor reports which gear range the transmission is actually in — the fact behind the selector display, the reverse lamps, and the rule that the starter only turns in park or neutral. Shift-by-wire designs duplicate it: with no mechanical cable to fall back on, the module wants two independent reports before it trusts either, especially about park.
Sensor B failing rarely strands the car; it removes the cross-check. The module can usually carry on watchfully using sensor A — but a car that misreports its range is a car that can roll away or start in gear, so expect caution: a flashing or wrong selector display, refusal to leave park, or a start that needs a second try.
These sensors fail the way all position sensors do — wear on the resistive track at the positions used most, water in a connector low on the gearbox, a harness chafed where it flexes. On cable-operated designs the sensor can also simply be out of adjustment, reading between ranges while the gearbox itself is exactly where it should be.
Likely causes
Start here
- Faulty transmission range sensor · specialist
- Misadjusted transmission range sensor · moderate
- Corroded transmission connector · specialist
Less common
- Damaged transmission wiring harness · specialist
Rare
- Faulty transmission control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about P2801.