P0025 code definition
Camshaft Position B - Timing Over-Retarded (Bank 2)
What the P0025 code means
P0025 is the OBD-II generic code indicating the Engine Control Module (ECM) has determined that the exhaust variable camshaft timing for bank 2 is more retarded than what the ECM has commanded it be. This over retarded timing condition could be during the advancing or retarding phase of the exhaust camshaft timing.
What causes the P0025 code?
The Variable Camshaft Timing (VCT) Oil Control Valve (OCV) is stuck in the open position.
The camshaft phaser is damaged and stuck in the retarded timing position.
There are oil flow problems to the VCT piston and phaser.
What are the symptoms of the P0025 code?
The ECM will turn on the Check Engine Light if the camshaft timing is in a lower timing position than expected.
The engine may be hard to start from the retarded timing position.
The engine may run rough and have reduced power.
Drivability symptoms may vary depending on how far the camshaft is out of position.
The engine may have excessive emissions from the tailpipe and fail emission testing.
How does a mechanic diagnose the P0025 code?
Visually checks the electrical connections and wire harness to the camshaft sensor, Oil Control Valve and the crankshaft sensor for any issues that may cause the problem
Clears codes and verifies whether the code returns before doing any further testing
Verifies that the engine oil is clean and is of the correct viscosity
Commands the OCV to 100% duty cycle to see if the camshaft timing changes
Performs manufacturer's specific pinpoint tests for the P0025 code and repairs as needed
Common mistakes when diagnosing the P0025 code
Follow these simple guidelines to prevent mistakes:
Verify the failure code is present before doing any repairs or replacing of components.
Check for any problems visually with the variable camshaft timing system components and wiring or connections.
Follow any pinpoint test step-by-step to isolate the failure on the system.
Do not replace any parts unless directed by the pinpoint or visual testing.
How serious is the P0025 code?
The vehicle may stall or hesitate and may be hazardous to drive safely.
Excessive fuel consumption and carbon fouling of the engine may happen over time if not repaired as soon as possible.
The engine's emissions may exceed Federal and local limits and fail emissions testing.
What repairs can fix the P0025 code?
- Clearing the fault codes and performing a road test to try and verify failure
- Changing the engine oil and filter to the proper oil viscosity
- Repairing or replacing the wiring or connection to the camshaft oil control valve.
- Replacing the camshaft oil control valve for bank 2 intake camshaft.
- Replace camshaft phaser for the bank 2 camshaft.
Additional comments for consideration regarding the P0025 code
The camshaft phaser and the passages through the camshaft and OCV are of specified sizes that are designed to use a specific viscosity oil. If the oil is too thick, then the oil may not be able to lubricate the camshaft and operate the VCT system as it was designed, which could cause failures of the camshaft and VCT systems.
Need help with a P0025 code?
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This article originally appeared on YourMechanic.com as P0025 OBD-II Trouble Code: Camshaft Position B - Timing Over-Retarded (Bank 2) and was authored by Jay Safford.