Medium severity
P0040Incorrect lambda sensor plugs or signals before the catalytic converter (Bank 1, Bank 2, Sensor 1)
Part
Lambda sensor
Part price
$88
At a workshop
$113
You save
$25
How to read code P0040
P
System
Powertrain (engine and transmission)
0
Code type
Generic code (SAE / OBD-II)
0
Subsystem
General system / auxiliary measurement
40
Fault number
Specific fault within the subsystem
Symptoms
- Fuel consumption issues
- Engine sputtering during driving
- Mixture ratio errors
Possible causes
- Incorrectly swapped electrical sensor plugs
- Mistaken wiring during sensor replacement
- Main wiring harness damage
Diagnostic steps
- 1Check the proper installation of the lambda sensor plugs in the engine compartment
- 2Compare live voltage readings of the sensors in the diagnostic software
- 3Analyze the engine wiring diagram
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Frequently asked questions about P0040
What does code P0040 mean?
P0040: Incorrect lambda sensor plugs or signals before the catalytic converter (Bank 1, Bank 2, Sensor 1).
What are the symptoms of code P0040?
Fuel consumption issues; Engine sputtering during driving; Mixture ratio errors.
What causes code P0040?
Incorrectly swapped electrical sensor plugs; Mistaken wiring during sensor replacement; Main wiring harness damage.
Can I drive with code P0040?
SAFE TO DRIVE – The fault does not immobilise the car, but diagnose it as soon as possible.
How much does it cost to fix code P0040?
The part (Lambda sensor) costs about $88, and a mechanic’s labour about $25.
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