P0845: Transmission fluid pressure sensor/switch B circuit fault

Transmission fluid pressure sensor/switch B circuit

Severity: Inspect soon

Kelley Blue Book rates P0845 moderate to serious and warns the car may enter limp mode.

It gets more serious if:

Not verified: The car goes into limp mode or shifts badly. Kelley Blue Book says limp mode is possible, but we found no source on whether you must stop.

P0845 in short

P0845 means the transmission computer sees a problem in the circuit of fluid pressure sensor or switch B, which reports hydraulic pressure inside the transmission. Wiring, the sensor, low fluid or the valve body can cause it. Shifts may turn rough or limp mode may start, so have it inspected soon.

Transmissions control shifts with hydraulic pressure. A pressure sensor or switch tells the computer whether the pressure matches what it commanded. If the reading is missing or does not make sense, it sets P0845.

Sources list wiring and connectors, the sensor or switch, low or contaminated fluid, and solenoids or valve body faults. Nissan found that some 2007-2008 CVT cars with P0840 and P0845 need a new control valve assembly.

A circuit code is not proof the sensor is bad. Check the fluid and wiring first, and have a shop read the module, because a basic code reader may not show transmission codes.

Most likely causes

Cause 1: Wiring or connector fault in the sensor circuit
Common general cause
Why it ranks here
TroubleCodes.net and Kelley Blue Book both list wiring and connectors, and this is a circuit code.
What would change this
Rises if the harness is chafed or the connector is corroded or has fluid in it.
Cause 2: Failed pressure sensor or switch
Common general cause
Why it ranks here
Both sources list the sensor or switch itself.
What would change this
Rises if the wiring tests good and the pressure reading is missing or stuck.
Cause 3: Low or contaminated fluid
Common general cause
Why it ranks here
Kelley Blue Book lists fluid, and Nissan ties odd-looking CVT fluid to this code.
What would change this
Rises if the fluid is low, discolored or smells burnt.
Cause 4: Control valve assembly (2007-2008 Nissan CVT)
Supported by vehicle data
Why it ranks here
Nissan NTB09-148 replaces the control valve assembly when P0845 is stored with P0840, P0744 and P1777.
What would change this
Rises on a covered Altima, Rogue or Sentra.
Cause 5: Loss of sensor voltage reference (2020-2021 Ford Escape)
Possible — needs testing
Why it ranks here
Ford SSM 50116 lists P0845 among many codes from a lost reference voltage. It is context, not a stated cause for this code.
What would change this
Rises if many unrelated sensor codes appeared at once on a covered Escape.
Cause 6: Transmission control module
Possible — needs testing
Why it ranks here
TroubleCodes.net lists the module as a possible cause.
What would change this
Rises only after the sensor, wiring and fluid are ruled out.
How to test the transmission control module (tcm)

What to test first

Start at step 1. Each result tells you what it means and where to go next.

Step 1: Read codes from the engine and transmission modules with a scan tool that supports both, before anything is cleared. Note other pressure or solenoid codes, and codes from other sensors.
Low riskTool: scan tool that reads the transmission module
- IfMany unrelated sensor codes are stored at once
  It meansSuspect a shared power or reference fault.
  Points to: Loss of sensor voltage reference (2020-2021 Ford Escape)
- IfP0840 or other CVT pressure codes are stored on a 2007-2008 Nissan
  It meansCheck the Nissan bulletin.
  Points to: Control valve assembly (2007-2008 Nissan CVT)
- IfP0845 alone
  It meansCheck the fluid.
  Go to step 2
Step 2: Check the fluid level and condition by the maker's method.
Use caution
Warning:Many transmissions are sealed. Do not open the fill plug without the maker's procedure, because the level depends on temperature.
- IfLow, discolored or burnt-smelling
  It meansFluid is the first suspect.
  Points to: Low or contaminated fluid
- IfFluid looks normal
  It meansInspect the wiring.
  Go to step 3
Step 3: Inspect the pressure sensor connector and harness for chafing, corrosion and fluid inside the plug.
Low risk
- IfDamage or corrosion is found
  It meansRepair it and retest.
  Points to: Wiring or connector fault in the sensor circuit
- IfWiring looks fine
  It meansA shop should test the sensor and circuit.
  Go to step 4
Step 4: Have a shop test the pressure sensor signal and circuit against the maker's specification.
Best left to a shopTool: scan tool and multimeter
Warning:Shop test. It needs the maker's specifications.
- IfThe signal is missing or stuck and the circuit is good
  It meansThe sensor or switch has failed.
  Points to: Failed pressure sensor or switch
- IfSensor and circuit are good
  It meansThe fault is inside the valve body or hydraulics.
  Points to: Control valve assembly (2007-2008 Nissan CVT)

Symptoms

Check engine light
Rough shifts or slipping
Limp mode Gets more serious: stop and have it checked.

How to fix

Step 1: Do not clear the code before the transmission module has been read.
Step 2: Ask a dealer whether your VIN has an open bulletin. Nissan has published one for 2007-2008 CVT cars.

Parts and cost context

Transmission control module (TCM):Do not replace the module for P0845 unless a test points to it. Nissan relearns calibration data in the module after a valve assembly repair.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Nissan

2007–2008 · Altima
Supported by vehicle data
Nissan NTB09-148 replaces the CVT control valve assembly when P0840 and P0845 are stored with P0744 and P1777. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.
2007–2008 · Rogue
Supported by vehicle data
Nissan NTB09-148 replaces the CVT control valve assembly when P0840 and P0845 are stored with P0744 and P1777. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.
2007–2008 · Sentra
Supported by vehicle data
Nissan NTB09-148 replaces the CVT control valve assembly when P0840 and P0845 are stored with P0744 and P1777. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

NTB09-148Status unverified
CVT check engine light with P0840, P0845, P0744 and P1777
2007–2008altima, rogue, sentra · NHTSA 10033269
Nissan replaces the control valve assembly on CVT models with these codes stored, then erases and relearns the calibration data in the transmission control module. Only the NHTSA flat-file summary was reviewed, not the bulletin itself.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
NTB09-044Status unverified
Discolored or odd-smelling CVT fluid with P0840 or P0845
2007–2008altima, rogue, sentra · NHTSA 10030088
Nissan describes CVT fluid that is discolored or smells with P0840 and/or P0845 stored. Only the NHTSA flat-file summary was reviewed, not the bulletin itself.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Ford

2020–2021 · Escape
Possible — needs testing
Ford SSM 50116 covers a loss of sensor voltage reference that can set many codes, P0845 among them. It is context only, not a repair for this code. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

SSM 50116Status unverified
Loss of voltage reference, many codes possible
2020–2021escape · NHTSA 10201593
Ford covers some Escapes that lose their sensor voltage reference, which can set many codes, P0845 among them. Context only: it does not give a transmission repair for P0845. Only the NHTSA flat-file summary was reviewed, not the bulletin itself.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

No curated relationships for P0845 yet.

All Transmission codes

P0845 questions

What is transmission fluid pressure sensor B?

It reports hydraulic pressure inside the transmission so the computer can check that shifts are being commanded correctly. P0845 means its circuit reads wrong.

Can I drive with P0845?

Have it inspected soon. Kelley Blue Book rates it moderate to serious, and limp mode is possible.

Sources and review

P0845 Code: Transmission Fluid Pressure Sensor/Switch B Circuit — Kelley Blue Book
P0845 Trouble Code: Transmission fluid pressure sensor/switch B circuit — TroubleCodes.net
NTB09-044: Discolored or odd-smelling CVT fluid, MIL on with P0840 and/or P0845 — Nissan North America
NTB09-148: MIL on with P0840, P0845, P0744, P1777 — Nissan North America
SSM 50116: 2020-2021 Escape loss of voltage reference (VREF) — Ford Motor Company

Last reviewed: October 15, 2026
Written by: Saurabh K.
Editorial review: Pending
Technician review: Technician review pending

This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

Severity: Inspect soon

Most likely causes

Cause 1: Wiring or connector fault in the sensor circuit

Cause 2: Failed pressure sensor or switch

Cause 3: Low or contaminated fluid

Cause 4: Control valve assembly (2007-2008 Nissan CVT)

Cause 5: Loss of sensor voltage reference (2020-2021 Ford Escape)

Cause 6: Transmission control module

What to test first

Step 1: Read codes from the engine and transmission modules with a scan tool that supports both, before anything is cleared. Note other pressure or solenoid codes, and codes from other sensors.

Step 2: Check the fluid level and condition by the maker's method.

Step 3: Inspect the pressure sensor connector and harness for chafing, corrosion and fluid inside the plug.

Step 4: Have a shop test the pressure sensor signal and circuit against the maker's specification.