P2088 – Camshaft position (CMP) actuator A, bank 1 – circuit low

Reinier

By Reinier (Contact Me)
Last Updated 2017-05-20
Automobile Repair Shop Owner

Trouble CodeFault LocationProbable Cause
P2088 Camshaft position (CMP) actuator A, bank 1 - circuit low Wiring short to ground, CMP actuator

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What Does Code P2088 Mean?

OBD II fault code P2088 is a generic code that is defined as “Camshaft position (CMP) actuator “A”, Bank 1 “Circuit low”, and is set when the PCM (Powertrain Control Module) detects a control voltage for the “A” camshaft that has fallen below a minimum permissible level, as calculated using battery voltage as a reference. Note that-

  • Code P2088 refers to issues in the VVT/VCT actuator’s control circuit, and NOT to differences in the relative position of the crankshaft in relation to the “A” camshaft, although a mismatch between the positions of the crankshaft and camshaft “A” may result from this code.
  • More precisely, code P2088 refers to the electrical control circuit of the Oil Control Valve, which is the component that regulates the oil pressure required to operate the actual actuator that rotates the camshaft to either advance, or retard the valve timing on the affected camshaft relative to TDC (Top Dead Centre) for cylinder #1.
  • “Camshaft position” refers to the position of camshaft “A” in degrees of rotation, relative to a base setting.
  • Camshaft actuator “A” usually refers to the intake camshaft on cylinder heads with dual camshafts.
  • “Bank 1”refers to the bank of cylinders that contains cylinder #1.

While design specifics vary between manufacturers, all VVT/VCT (Variable Valve Timing/Variable Camshaft Timing) systems use engine oil pressure to control/adjust the position of the camshafts to increase engine power, and to reduce exhaust emissions.

In terms of operation, the position of the camshaft, which is camshaft “A”, in the case of code P2088, is monitored with a dedicated sensor. The actual position of camshaft “A” is then compared to that of the other camshaft (on engines with dual camshafts), as well as the position of the crankshaft. Depending on operating conditions, throttle inputs from the driver, and feedback from other driveability sensors, the PCM can adjust the valve timing to answer to the inputs from the driver, or to automatically increase engine power at certain engine speeds and loads.

Being able to adjust the valve timing to suit the operating conditions at any given moment has the advantage that the engine can always perform at peak efficiency, while using less fuel and reducing harmful exhaust emissions at the same time. However, for the system to work properly, the Oil Control Valve’s electrical circuit has to be in perfect working condition. Both the input and feedback (signal) voltages have to be within predefined limits: if they are not, the PCM is unable to determine the camshaft’s actual deviation from a base setting, which has serious negative effects on engine efficiency, fuel economy, and exhaust emissions.

As a practical matter, when the PCM detects a lower than expected input voltage to the Oil Control Valve, it recognizes that it cannot control the valve timing effectively, and it will set code P2088 as a result. Note that on some applications the PCM will set code P2088 on the first failure while on others the PCM will set code P2088 and illuminate warning light only on the second failure. Also note that on applications that require two failure cycles before a warning light is illuminated, the code may be present as “pending”.

The image below shows a typical Oil Control Valve. This is the part that ultimately controls the VVT/VCT system, but for the system to work correctly, the valve’s electrical control system needs to be in perfect working order.

VVT Oil Control Valve

What are the common causes of code P2088?

Common causes of code P2088 could include the following-

  • Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors
  • Low system voltages caused by defects in the battery and/or charging system. Note however that these conditions will almost invariably be indicated by dedicated codes
  • Defective Oil Control Valve
  • Misaligned timing marks due to careless assembly after major repairs to the timing system or assembly of an engine. Note that this will usually be indicated by codes other than P2088, such as codes relating to excessively advanced or retarded valve timing
  • Failed or failing PCM. Note that this is a rare event, and the fault must be sought elsewhere before any control module is replaced

What are the symptoms of code P2088?

Common symptoms of code P2088 could include the following-

  • Stored trouble code, and possibly an illuminated warning light
  • Other codes relating to misfires or exhaust emissions may be present
  • Hard, or even no start conditions may be present in some cases
  • The engine may exhibit some power loss
  • Idling speed may fluctuate
  • Idling may be rough, and/or erratic, or the engine may not idle at all
  • Fuel consumption may increase
  • Catalytic converter damage or failure may occur due to poor combustion
  • Vehicle may not pass an emissions test

How do you troubleshoot code P2088?

NOTE #1: Be sure to check the electrical system voltage before starting a diagnostic procedure for this code. Low system voltages due to a defective battery or charging system can have unpredictable results, which can include the setting of random codes.

NOTE #2: If code P2088 appears immediately after a timing belt or timing chain replacement, be sure to check that all timing marks align properly (as per the diagrams in the manual) before starting an electrical diagnosis of the control system. Reset the timing marks as required as per the instructions in the repair manual.     

Step 1

Record all fault codes present, as well as all available freeze frame data. This information could be of use should an intermittent fault be diagnosed later on.

NOTE: If any additional codes are present, pay particular attention to codes that precede P2088, since these codes could have contributed to P2088. Investigate and resolve all codes preceding P2088 in the order in which they were set and stored before attempting a diagnosis of P2088. Failure to do this will almost certainly result in a wrong diagnosis, wasted time, and the almost certain unnecessary replacement of parts and components.

Step 2

Assuming that no other codes are present, refer to the manual for the application to identify and locate all affected wiring and components. Use this opportunity to determine the color-coding, location, routing, and function of each wire in the affected harness.

NOTE: To prevent a misdiagnosis, consult the manual to verify which camshaft / actuator is labelled with the letter “A”, since manufacturers do not always conform to convention when it comes to labelling components.

Step 3

Perform a thorough visual inspection of the affected wiring. Look for damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors and make repairs, or replace wiring as required.

Clear all codes after repairs are complete, and operate the vehicle normally before rescanning the system to see if the code returns.

Step 4

If the code persists, prepare to perform resistance, continuity, ground integrity, and reference voltage tests on all associated wiring. Be sure however to disconnect the sensor and its wiring from the PCM to prevent damage to the controller during resistance/continuity tests.

Compare all obtained readings with the values stated in the manual, and make repairs or replace wiring as required to ensure that all electrical values fall within the ranges specified by the manufacturer. Note that the Oil Control Valve itself forms part of the control circuit, and as such, its internal resistance/continuity must be tested as well. Replace the valve with an OEM part if its resistance/continuity does not agree with the value stated in the manual. Note that some applications require the replacement of camshaft and crankshaft position sensors as a complete set; consult the manual for the application to see if this applies to that application.

Clear all codes after repairs are complete, and operate the vehicle normally before rescanning the system to see if the code returns.

NOTE: Pay particular attention to the Oil Control Valve’s power supply circuit during this step. Check for short circuits to battery negative (ground), and perform the wiggle test on all connectors in this circuit to check for intermittent poor connections. Replace, rather than repair all suspect connectors and wiring to prevent possible issues with poorly executed repairs later on.

Step 5

If code P2088, or any other code for that matter, does not return the repair can be considered as successful. However, in the unlikely event that code does return, suspect either a defective PCM, or an intermittent fault that was not resolved during the diagnostic procedure.

Bear in mind though that PCM failure is exceedingly rare, so the problem is far more likely to involve an intermittent fault. If this is suspected, repeat all tests on all wiring until the fault is found and repaired, or simply replace the relevant harness with an OEM replacement. Doing this is often more cost effective and more effective overall than spending hours looking for an intermittent fault that may never be found.

Step 6

If no codes return after completing Step 5, perform the required after repair procedure(s) as per the instructions in the manual id such procedures are applicable to the application.

Codes Related to P2088

  • P2089 – Relates to “A Camshaft Position Actuator Control Circuit High –  Bank 1”

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