Failed transmission fluid pressure sensor/switch (both sources; OBD-Codes.com rates it the likely cause). Open circuit, short to voltage or short to ground in the sensor signal wiring, or a corroded connector (both sources mention wiring). Low transmission fluid level (RepairPal). Internal mechanical transmission problems such as internal leaks, valve body check ball problems, low line pressure or a stuck valve (OBD-Codes.com). Faulty PCM or TCM (both sources; OBD-Codes.com rates it unlikely and says a replacement must be programmed). The sources differ: RepairPal adds low fluid level, while OBD-Codes.com adds internal mechanical problems.

Clean or repair corroded connectors and damaged wiring. Top up the transmission fluid to the correct level. Replace the transmission fluid pressure sensor/switch. Repair internal transmission or valve body problems when diagnosis points there. Replace and program the PCM/TCM only after other causes are ruled out.

P0846🔧 Transmission / Fluid pressure sensorsStop and fix promptly

P0846: Transmission Fluid Pressure Sensor/Switch B Circuit Range/Performance (Meaning, Causes, Fixes)

Q: What does P0846 mean?

P0846 means the transmission computer is getting a signal from transmission fluid pressure sensor/switch "B" that doesn't match what it expects. The most likely cause is a failed pressure sensor/switch, followed by wiring or connector problems, low fluid, internal transmission problems, and less often a faulty PCM/TCM. An automatic transmission uses fluid pressure to apply its clutches and change gears. A transmission fluid pressure sensor/switch (TFPS) turns that pressure into an electrical signal so the powertrain control module (PCM), or a separate transmission control module (TCM), can tell the operating pressure or when a shift is happening. OBD-Codes.com says the TFPS is usually attached to the side of the valve body inside the transmission, though on some vehicles it screws into the side of the case. It says P0846 is set when the "B" input doesn't match the normal operating voltages stored in the PCM/TCM's memory, and that it can also be caused by mechanical problems inside the transmission, such as internal leaks, cracked or missing check balls in the valve body, low line pressure or a stuck valve. RepairPal describes it more broadly: the PCM or TCM sets P0846 when it detects an issue with the hydraulic clutch or the pressure switch. The two sources also word the code's name differently: OBD-Codes.com calls it "Circuit Range/Performance", while RepairPal lists it simply as "Circuit". It is a generic OBD-II code; OBD-Codes.com lists Jeep, Dodge, Mazda, Nissan, Honda and GM among makes that use it, and which sensor is "B" depends on the vehicle, so check a repair manual for yours. Its sibling codes for the same sensor are P0845 (circuit), P0847 (circuit low), P0848 (circuit high) and P0849 (circuit intermittent).

Q: Can I keep driving with P0846?

Stop and fix promptly. Get it diagnosed soon. RepairPal rates P0846 Urgent, meaning it can cause severe damage or be unsafe. OBD-Codes.com is milder: it says that because this is usually an electrical fault the PCM/TCM can compensate to some degree, though it may change how the transmission shifts or put it in limp mode (starting off in 2nd or 3rd gear). If shifting feels wrong or the car is stuck in one gear, drive gently and avoid highway and heavy-traffic driving until it's checked.

Reviewed 2026-10-24 · Based on 2 cited source(s)

What P0846 means

An automatic transmission uses fluid pressure to apply its clutches and change gears. A transmission fluid pressure sensor/switch (TFPS) turns that pressure into an electrical signal so the powertrain control module (PCM), or a separate transmission control module (TCM), can tell the operating pressure or when a shift is happening. OBD-Codes.com says the TFPS is usually attached to the side of the valve body inside the transmission, though on some vehicles it screws into the side of the case. It says P0846 is set when the "B" input doesn't match the normal operating voltages stored in the PCM/TCM's memory, and that it can also be caused by mechanical problems inside the transmission, such as internal leaks, cracked or missing check balls in the valve body, low line pressure or a stuck valve. RepairPal describes it more broadly: the PCM or TCM sets P0846 when it detects an issue with the hydraulic clutch or the pressure switch. The two sources also word the code's name differently: OBD-Codes.com calls it "Circuit Range/Performance", while RepairPal lists it simply as "Circuit". It is a generic OBD-II code; OBD-Codes.com lists Jeep, Dodge, Mazda, Nissan, Honda and GM among makes that use it, and which sensor is "B" depends on the vehicle, so check a repair manual for yours. Its sibling codes for the same sensor are P0845 (circuit), P0847 (circuit low), P0848 (circuit high) and P0849 (circuit intermittent).

Severity: can I keep driving?

Stop and fix promptly

Get it diagnosed soon. RepairPal rates P0846 Urgent, meaning it can cause severe damage or be unsafe. OBD-Codes.com is milder: it says that because this is usually an electrical fault the PCM/TCM can compensate to some degree, though it may change how the transmission shifts or put it in limp mode (starting off in 2nd or 3rd gear). If shifting feels wrong or the car is stuck in one gear, drive gently and avoid highway and heavy-traffic driving until it's checked.

Common symptoms

Check engine light on (OBD-Codes.com)
Change in shift quality, or the transmission doesn't shift properly (both sources)
Car starts off in 2nd or 3rd gear because the transmission is in limp mode (OBD-Codes.com)
Increased fuel consumption (RepairPal)

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Failed transmission fluid pressure sensor/switch (both sources; OBD-Codes.com rates it the likely cause)
Open circuit, short to voltage or short to ground in the sensor signal wiring, or a corroded connector (both sources mention wiring)
Low transmission fluid level (RepairPal)
Internal mechanical transmission problems such as internal leaks, valve body check ball problems, low line pressure or a stuck valve (OBD-Codes.com)
Faulty PCM or TCM (both sources; OBD-Codes.com rates it unlikely and says a replacement must be programmed)
The sources differ: RepairPal adds low fluid level, while OBD-Codes.com adds internal mechanical problems

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Read all stored codes. OBD-Codes.com says that if power-related codes or more than one pressure sensor/switch code are stored with P0846, diagnose those first, since they may be the reason for it.
Check for technical service bulletins (TSBs) for your vehicle; a known issue may have a known fix.
Check the transmission fluid level and condition.
Find the pressure sensor/switch connector and inspect the wiring for rubbing, bare wires, burn spots or melted plastic. Unplug it and look for burned or green, corroded terminals; clean them with electrical contact cleaner and a plastic brush, let them dry and apply electrical grease.
Clear the code and see if it comes back. OBD-Codes.com says corroded external connections are the most common problem for this code.

Typical fixes

Clean or repair corroded connectors and damaged wiring
Top up the transmission fluid to the correct level
Replace the transmission fluid pressure sensor/switch
Repair internal transmission or valve body problems when diagnosis points there
Replace and program the PCM/TCM only after other causes are ruled out

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

The transmission shifts badly, is stuck in limp mode or the code comes back after cleaning the connections
On many vehicles the sensor is mounted on the valve body inside the transmission, so replacing it means removing the transmission pan
OBD-Codes.com's circuit tests use a digital voltmeter and ohmmeter and need the manufacturer's specifications: reference voltage is 12 volts or 5 volts depending on the vehicle, and sensor resistance varies by model
A replacement PCM/TCM must be programmed or calibrated to the vehicle

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Is P0846 serious?

It can be. RepairPal rates it Urgent. OBD-Codes.com says the computer can often compensate because it is usually an electrical fault, but shifting may change or the transmission may go into limp mode. Get it checked soon.

Can I keep driving with P0846?

Only gently and for short trips until it's diagnosed. If the car is stuck in one gear or shifts badly, avoid highway driving and get it looked at.

Is P0846 always the pressure sensor?

No. OBD-Codes.com rates a failed sensor as the likely cause but says corroded connections are the most common issue and internal transmission problems can also set it. RepairPal adds low fluid and wiring. Check fluid and connections before replacing the sensor.

What is the difference between P0845, P0846, P0847, P0848 and P0849?

All are for transmission fluid pressure sensor/switch "B". OBD-Codes.com lists P0845 as circuit, P0846 as circuit range/performance, P0847 as circuit low, P0848 as circuit high and P0849 as circuit intermittent.

How much does it cost to fix P0846?

Neither source gives a repair cost. It can range from cleaning a connector or adding fluid to replacing the sensor or repairing the transmission, so get a diagnosis and a written estimate first.

Sources

Last reviewed 2026-10-24. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.