PowertrainP0840

Caution

Severity: Caution - get it checked when you can

Transmission Fluid Pressure Sensor/Switch A Circuit

32 brands affected · Generic SAE J2012 description.

Key terms: SAE J2012: the standard generic code list · Powertrain: engine, transmission and emissions

1What it means in plain English

This range normally covers the transmission control system, but some manufacturers use P07-P09 codes for unrelated functions (fuel pump control, air-mix motors, lighting or windows). Check the description before assuming it is a transmission fault.

2Common causes

Low or dirty transmission fluid
Faulty shift solenoid
Faulty speed sensor
Wiring or connector fault
Internal transmission wear

3Can I drive?

Caution · drive with care

If the transmission slips, jerks, will not shift, or a transmission temperature warning is on, stop driving and let it cool: continuing can cause expensive damage. If the code names a different system (for example the fuel pump), treat it on its own terms; a fuel-pump control failure can stall the car, so have it checked before driving further. Otherwise drive gently to a workshop.

This page gives general information. It is not professional advice. For a definite diagnosis and a repair quote, ask a qualified mechanic to inspect the car.

4Brand data 32

Brand	Code	Description	System
Ashok Leyland CV	P0840	Transmission Fluid Pressure Sensor/Switch A Circuit SAE	Powertrain
BAIC Motor	P0840	Secondary pressure sensor fault Brand	Powertrain
BMW	P0840	Transmission Fluid Pressure Sensor/Switch A Circuit SAE	Powertrain
BYD	P0840	Secondary pressure sensor fault Brand	Powertrain
Chery	P0840	Pressure sensor Brand	Powertrain
Daewoo	P0840	Transmission Fluid Pressure Sensor/Switch A Circuit Brand	Powertrain
Daihatsu	P0840	Belt clamping pressure sensor system Brand	Powertrain
DFFS	P0840	Hydraulic sensor switch failure Brand	Powertrain
DFFX	P0840	Transmission Fluid Pressure Sensor/Switch A Circuit Brand	Powertrain
DFXK	P0840	Transmission Fluid Pressure Sensor/Switch A Circuit Brand	Powertrain
EOBD	P0840	Litar sensor/suis tekanan cecair transmisi 'A' Brand	Powertrain
Geely	P0840	Secondary Pressure Sensor Fault Brand	Powertrain
GM	P0840	Transmission pressure switch solenoid C circuit Brand	Powertrain
Great Wall	P0840	Secondary pressure sensor fault Brand	Powertrain
Hafei	P0840	Transmission Fluid Pressure Sensor/Switch A Circuit Brand	Powertrain
Holden	P0840	Transmission Fluid Pressure Switch 1 Signal Brand	Powertrain
Honda	P0840	Transmission Fluid Pressure Sensor/Switch A Circuit SAE	Powertrain
Hyundai	P0840	Transmission Fluid Pressure Sensor/Switch A Circuit SAE	Powertrain
Isuzu	P0840	Transmission Fluid Pressure Sensor/Switch A Circuit SAE	Powertrain
Land Rover	P0840	Transmission Fluid Pressure Sensor/Switch A Circuit SAE	Powertrain
Mitsubishi	P0840	Secondary pressure SNS. circuit Brand	Powertrain
Nissan	P0840	Transmission Fluid Pressure Sensor/Switch A Circuit SAE	Powertrain
Opel	P0840	Transmission Fluid Pressure Sensor/Switch A Circuit SAE	Powertrain
Perodua	P0840	Belt clamping pressure sensor system Brand	Powertrain
Peugeot	P0840	Transmission Fluid Pressure Sensor/Switch A Circuit SAE	Powertrain
Proton	P0840	Secondary pressure SNS. circuit Brand	Powertrain
Saab	P0840	Stromkreis Magnetventil C Getriebedruckschalter Brand	Powertrain
MG (SAIC)	P0840	Odd Clutch Pressure Sensor Circuit Brand	Powertrain
Suzuki	P0840	Transmission Fluid Pressure Sensor / Switch 'A' Circuit Brand	Powertrain
Tata	P0840	Transmission Fluid Pressure Sensor/Switch 'A' Circuit Brand	Powertrain
Toyota	P0840	Hydraulic sensor switch failure Brand	Powertrain
Volkswagen	P0840	Gearbox hydraulic pressure sender 1 electrical fault in Brand	Powertrain

Legend: SAE is the generic J2012 description; Brand is text taken from that manufacturer’s data. Manufacturer rows keep the wording and language of the source data, and non-English text is tagged so screen readers pronounce it correctly.

5Extended variant codes 3

These 7-character codes are manufacturer-specific variants of P0840 and may be reported by some scan tools.

Brand	Code	Description	System
Mercedes-Benz	P084000	Istdruck zu Solldruck Drucksensor unplausibel - Offset-Fehler Brand	Powertrain
Mercedes-Benz	P084016	Transmission Fluid Pressure Sensor/Switch 'A' Circuit Brand	Powertrain
Mercedes-Benz	P084064	Istdruck zu Solldruck Drucksensor unplausibel Brand	Powertrain

6Related codes

Browse Pxxx codes or P084xx codes.