P0021 Engine Trouble Code
What is P0021?
With P0021, you may drive for several weeks with a malfunctioning MAF sensor, but expect decreased fuel economy and eventual stalling. Shop replacement costs $240–$400 depending on vehicle. The labour is straightforward, with most cost from the part itself.
Code Information
| Code Type: | OBD-II Powertrain (P) Trouble Code |
| System: | Powertrain |
| Code: | P0021 |
P0021 Symptoms
Check Engine Light
Illuminated dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration
Starting Problems
Difficulty starting the engine
P0021 Code Structure
Understanding what each digit means in the P0021 powertrain trouble code:
| P | 0 | 0 | 2 | 1 |
|---|---|---|---|---|
| Powertrain Code | Intake Valve Control Solenoid Circuit Low | Ambient Air Temperature Sensor Circuit Low | Turbocharger Boost Sensor A Circuit Low | Crankshaft Position Sensor A Circuit Low Input |
How to Fix P0021
Diagnostic Steps:
Poor running symptoms align with MAP sensor malfunction. In some cases, a faulty MAP sensor will not trigger a code. The issue may represent separate wiring concerns requiring individual diagnosis.
Repair Solution:
VSS concerns may stem from noisy input signals caused by RFI/EMI from ignition wires, charging circuits, or aftermarket equipment. Verify VSS reads 0 mph when transmission is in Park.
Technical Notes:
P0021 DTC specifically relates to camshaft timing. When cam timing is over-retarded, the check-engine light illuminates and this code sets. Verify VCT solenoid operation and check for contamination.
P0021 Description
P0021 OBD-II Trouble Code: Camshaft Position A Timing Over-Advanced or System Performance Bank 2 is the generic definition for the P0021; however your vehicles manufacturer may have a different definition for the P0021 code.
Main Cause
The primary reason for P0021 OBD-II Engine Trouble Code is: Ambient Air Temperature Sensor Circuit Low.