P000B – “B” Camshaft Position Slow Response

Reinier

By Reinier (Contact Me)
Last Updated 2020-08-19
Automobile Repair Shop Owner

CodeFault LocationProbable Cause
P000B B Camshaft Position Slow Response
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What Does Code P000B Mean?

OBD II fault code P000B is a generic trouble code that is defined as “B” Camshaft Position Slow Response Bank 1”, and is set when the PCM (Powertrain Control Module) detects a slow response from the camshaft labeled “B” on cylinder bank # 1 on V-type engines that are fitted with variable valve timing. Note that-

  • This code only applies to engines with VVT (Variable Valve Timing) systems
  • “Slow response” refers to the camshaft being slow to respond to commands from the PCM to either advance or retard
  • While “Camshaft B” typically refers to exhaust camshafts, this labeling convention is not observed by all manufacturers, so be sure to consult reliable service information to identify the camshaft labeled “B” on the affected application
  • “Bank 1” refers to the bank of cylinders on V-type engines that contains cylinder #1

The primary purpose of VVT (Variable Valve Timing) systems is to improve engine power and performance while improving fuel economy and decreasing emissions at the same time. In terms of operating principles, variable valve timing systems use pressurized engine oil to act on actuators that rotate the camshafts either against or with the camshaft’s normal direction of rotation.

By rotating the camshaft against its normal direction of rotation, the valve timing on that camshaft is advanced, i.e., the valves open sooner than they would normally have opened while rotating the camshaft with its normal direction of rotation has the opposite effect, i.e., the valves open later than they would normally have opened. Note that on some engines, only the intake camshaft can be adjusted, while on others, both the intake and exhaust camshafts can be adjusted both relative to each other, and relative to abase setting.

As a practical matter, adjustable camshafts return to their “normal” or base setting when the engine is not running (or is running at low speeds), and the PCM obtains data from dedicated camshaft position sensors to confirm this setting when the ignition is turned on. This information is used to identify cylinder #1, as well as to calculate appropriate ignition and fuel injection timing strategies for cylinder #1 when the engine is cranked. This information is also compared to the position of the crankshaft relative to a fixed reference point, and the position of all other adjustable camshafts on the engine for purposes of monitoring the correlation between the crankshaft and all camshafts on the engine.

In practice, VVT systems are controlled, managed, and monitored continuously by the PCM that obtains data from several engine and driveability sensors to determine under what conditions the VVT system should be activated. When the PCM deems operating conditions suitable, it opens oil control solenoids to allow pressurized engine oil to act on the camshaft actuators, and in a fully functional system, the PCM expects the desired change in valve timing to occur in a predetermined amount of time, which is typically measured in milliseconds.

However, in cases where the change in valve timing takes longer than expected, miscorrelations between camshafts and/or the crankshaft occur, which has the effect of increasing both fuel consumption and exhaust emissions, while reducing engine power, at the same time. Therefore, if the PCM detects that the camshaft labeled “B” on bank 1 is slow to respond to commands to alter its position relative to its normal base setting, it will recognize that it cannot control the valve timing effectively, and it will set code P000B and illuminate a warning light as a result.

Where is the P000B sensor located?

This image shows the location (arrowed) of a camshaft position sensor on a 2014 VW Jetta. Note though that the locations and appearance of camshaft position sensors vary greatly between applications. In some cases, like the example shown here, the sensor is easily accessible, but in many other instances, camshaft position sensors can be hidden inside timing covers, behind unrelated components, or under cosmetic engine covers. Therefore, it is recommended that reliable service information be consulted to identify and locate the affected sensor correctly to prevent the inadvertent replacement of the wrong parts.

What are the common causes of code P000B?

Common causes of code P000B are largely similar across all applications, and could include one or more of the following-

  • Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors
  • Defective oil control solenoid
  • Defective or malfunctioning camshaft actuator
  • Dirty, degraded, contaminated, or unsuitable engine oil
  • Insufficient oil pressure
  • In some cases, damaged engine timing components such as worn or damaged timing chains, timing chain guides, or timing sprockets can contribute to code P000B

What are the symptoms of code P000B?

Symptoms of code P000B are largely similar across all applications, but note that the severity of one or more symptoms listed here may vary between applications and engine designs/types-

  • Stored trouble code and illuminated MIL (CHECK ENGINE) light
  • In some cases, multiple other codes relating to camshaft/crankshaft correlations may be present along with P000B
  • Depending on both the application and the nature of the problem, mechanical noises may be present
  • Fuel consumption may increase noticeably
  • Varying degrees of power loss may be present
  • Exhaust emissions may increase to the point where the vehicle may fail an emissions test, or where catalytic converter failure may occur
  • Engine may run roughly at all speeds, or only at some speeds
  • Engine may stall frequently and/or unpredictably
  • Engine may be hard to start both when it is hot and cold
  • Gear shifts may be harsh, erratic, or unpredictable