P1011 – Camshaft reset valve faulty – clean valve (Volvo)

By Bojan Popic (Contact Me)
Last Updated 2022-12-02
Master Mechanical Engineer

Manufacturer Specific Definitions for P1011

Table of Contents

1. What Does Code P1011 Mean?
2. Where is the P1011 sensor located?
3. What are the common causes of code P1011?
4. Get Help with P1011

What Does Code P1011 Mean?

The P1011 is a manufacturer-specific trouble code that Volvo describes differently depending on the specific model and engine. Often, this will cause confusion and lead to misdiagnosis and unwanted repairs. But with Volvo’s cars, this code is the most common in models with 5-cylinder non-turbo engines from the early 2000s. With that in mind, we will focus on what might cause the P1011 trouble code in these vehicles.

Depending on the exact year of the car, the description will be either a ‘Camshaft reset valve faulty – clean valve’ or ‘internal fault in knock sensor circuit’. But despite the difference, the problem is most likely caused by variable valve timing issues.

Where is the P1011 sensor located?

All Volvo’s 5-cylinder engines, popular in cars such as S60 or V70, are equipped with variable valve timing, or VVT. This device sits at the end of the intake camshaft and alters the position between it and the crankshaft. Depending on the driving condition, the intake camshaft will be advanced or retarded. By doing so, the VVT increases airflow into the cylinders at all engine speeds, which improves performance and consequently reduces fuel consumption.

The actual work of camshaft adjustment is done by a component called VVT solenoid. This is a simple hydraulic device in which pressurized engine oil moves its internals to one side or the other. In all said engines, the VVT solenoid is fitted at the top of the cylinder head, at its timing side. Also, as it operates the intake timing, it will be aligned with the corresponding camshaft, which is the one facing the radiator.

What are the common causes of code P1011?

Jammed VVT solenoid

The most common cause for the P1011 trouble code in Volvo cars is the VVT solenoid itself. In most cases, the engine oil that circulates inside it will form build-ups, which obstruct its movement. This will usually start as a sporadic happening, but it will become more frequent over time. Luckily, it is possible to clean the solenoid and remove build-ups from it. But for this, it has to be removed from the engine, taken apart, and then cleaned thoroughly using a suitable cleaning agent. Leaving it to soak overnight has proved to be the most efficient method. But If this only yields limited results the VVT solenoid will have to be replaced. In both cases, when refitting it, the new gasket between its housing and the cylinder head will be needed.

Inadequate engine oil 

The hydraulic VVT mechanism, to operate correctly, needs a steady supply of pressurized engine oil. Any irregularities here may offset its function, which may then trigger the P1011 trouble code. In essence, this happens due to oil degradation, caused by insufficient maintenance or usage of oils of inadequate quality. Because of this, engine oil has to be replaced within recommended intervals. And, equally important, high-quality products need to be used here. For the 2.4 engines considered here, the engine oil that meets ACEA A1/B1 specifications is recommended.

Poor quality fuel or sensor issues

In some rare occasions, the P1011 trouble code may appear after filling up the car with low-quality gasoline or if the fuel filter is clogged. A similar may happen if the MAF sensor or the oxygen probe is dirty. All these situations will offset the air-fuel mixture, which the ECM will try to compensate for by adjusting various engine running parameters. Among other things, it may operate the VVT mechanism more sharply, which can cause problems if its solenoid is already on its last legs.

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