P0029 Code- Exhaust Valve Control Solenoid Circuit Range/Performance Bank 2

What Does Code P0029 Mean

P0029 is the OBD-II generic code indicating the engine control module (ECM) has determined that the variable valve lift solenoid for the exhaust valves for bank 2 takes too long to engage or does not engage.

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Possible symptoms

• Engine Light ON (or Service Engine Soon Warning Light)

What causes the P0029 code?

• The ECM activates the exhaust valve solenoid for bank 2 and the valve lift does not shift.
• The exhaust variable valve lift solenoid is short circuited internally.
• The variable valve lift solenoid has an open circuit internally.
• The wiring or connections to the exhaust valve solenoid or the ECM is shorted or open.

Troubleshooting P0029

NOTE: When diagnosing code P0029, start the procedure by inspecting the engine for oil leaks that could have reduced the engine oil level. Repair oil leaks as required, top off the oil level, clear the code, and operate the vehicle. Rescan to see if the code returns. If the code persists, proceed as follows-

Step 1

Check the engine oil level, and adjust the level to the correct mark. Clear the code and operate the vehicle to see if the code returns.

NOTE: At this point, it is important to determine if the engine is filled with suitable oil. For instance, mineral oil in an engine that requires synthetic oil can cause the formation of sludge, gums, and varnishes that can interfere with the correct operation of actuators and control valves/mechanisms. Replace the oil and filter if there is any doubt about the type, grade, viscosity, or age of the engine oil.

Step 2

If the engine oil is at the correct level, and of the correct type and grade, perform an oil pressure test to verify that the oil pressure is within specification. Low oil pressure is major cause of code P0029. If the oil pressure does not conform to specification, locate and repair the cause before commencing with the diagnostic procedure.

Step 3

If the oil pressure is within specification, perform a thorough inspection of all related wiring and connectors. Repair all defects as required, but be sure to check the circuit for reference voltage, continuity, and ground contact. Be sure however to disconnect all control modules before commencing continuity checks. Consult the relevant manual to determine the color-coding, location, and function of each wire in the connector, as well as the exact values of the reference voltage.

Step 4

If repairs to the wiring/connectors were made, clear the code, operate the vehicle, and rescan to see if the code is still present. If the code persists, there may be an intermittent fault present, and you may have to allow it to worsen before an accurate diagnosis can be made.

Step 5

If no faults are found during the inspection and testing of the electrical circuit, remove the actuators and control valve(s)/mechanism(s), and inspect them for evidence of damage, or the presence of sludge that could interfere with their operation. Clean all components as required, and test their operation before re-installing them.

NOTE: With some scanners and code readers, it is possible to operate the actuators or control valves manually. Where this is not possible, consult the relevant manual on the correct testing procedures, but be sure to follow the directions exactly to ensure a valid diagnosis.

If the actuator or control valve/mechanism works when it is operated manually, it is likely that internal oil passages in the engine may be blocked. Reinstall all components, and perform an engine flush with a suitable agent to dissolve any possible sludge or blockage(s) in the VVT or VCS oil supply circuit.

Step 6

Change the oil and filter to remove the engine flush agent, clear all codes, and operate the vehicle to see if the code returns. It is very unlikely to happen at this point, but not impossible, so if the code persists after an engine flush, replace the actuator or control valve/mechanism, and retest the vehicle. If despite all previous repair attempts the fault persists, there are three possibilities to consider.

One is that the blockage in the oil supply circuit is not fully cleared, and the other is an intermittent fault that could be extremely challenging to find and resolve, which means that the fault may have to be allowed to worsen considerably before an accurate diagnosis and definitive repair could be made.

One other, albeit unlikely, possibility involves a possible defective PCM, but PCM failures are exceedingly rare, meaning that all other avenues must be explored to trace and correct the root cause of code P0029 before the PCM is replaced.