Experiencing the frustration of an engine light and performance issues in your vehicle, especially with an OBD2 code like P06DD, can be daunting. This code often points to problems within your vehicle’s oil pressure control system, specifically the oil pump control circuit. Mechanics might suggest costly repairs, sometimes involving significant engine disassembly. However, for certain vehicles like the 2014 GMC Sierra 4WD, a less invasive and significantly cheaper DIY solution exists. This guide will walk you through a method to potentially resolve the P06DD code using a lacquer thinner flush, saving you time and money.
Understanding OBD2 Code P06DD
The Obd2 Code P06dd is formally defined as “Oil Pump Control Circuit Performance/Stuck Off.” This indicates that your vehicle’s Powertrain Control Module (PCM) has detected an issue with the oil pump’s control circuit. Often, this isn’t a complete oil pump failure, but rather a problem with the oil pump solenoid. This solenoid can become stuck or clogged due to varnish or debris buildup within the oil system. When this happens, the oil pump may not regulate oil pressure correctly, leading to the P06DD code and potentially affecting engine performance, including disabling fuel-saving features like cylinder deactivation (V4 mode in some GMC/Chevrolet vehicles).
The DIY Lacquer Thinner Flush Solution
Instead of immediately resorting to expensive component replacements requiring transaxle removal (in 4WD vehicles), consider a targeted cleaning approach. This method utilizes a lacquer thinner flush to dissolve varnish and clear blockages from the oil pump solenoid and its passages. This DIY fix is significantly cheaper and less labor-intensive, potentially saving you thousands of dollars in repair costs. It’s crucial to emphasize that this method is performed with the engine off and is designed to clean the solenoid without physical disassembly.
Step-by-Step Guide to Performing the Flush
Safety First: Lacquer thinner is flammable and harmful. Work in a well-ventilated area, wear appropriate safety glasses and gloves, and ensure no open flames or sparks are present. This procedure also involves cranking the engine with the starter motor without the engine starting, so understand the steps thoroughly before proceeding.
-
Drain Engine Oil: Begin by draining the engine oil completely from the oil pan using the drain plug. Replace the drain plug once the oil has fully drained.
-
Remove Oil Filter: Unscrew and remove the oil filter. Position a drain pan beneath the oil filter housing to catch any spillage.
-
Fill with Lacquer Thinner (via Dipstick Tube): This is a critical step. Carefully pour approximately 6 quarts of lacquer thinner into the engine oil pan. Crucially, pour the lacquer thinner through the crankcase dipstick tube. Avoid pouring it into the normal oil filler cap opening, as this could introduce lacquer thinner to parts like valve seals, potentially causing swelling of natural rubber components.
-
Prepare for Engine Cranking (Starter Relay Jump): Locate the fuse box, typically under the hood. Identify the starter relay. Consult your vehicle’s owner’s manual or fuse box diagram if needed. Remove the fuse box cover to access the relays.
-
Jump the Starter Relay: Create a small jumper wire. Using the jumper wire, carefully jump the starter relay by connecting the diagonal pin holes in the relay socket. Do NOT use the ignition key to turn over the engine. Using the key could engage the ignition system, potentially igniting the lacquer thinner fumes and causing an explosion hazard. Jumping the starter relay directly cranks the engine without ignition.
-
Crank Engine in Short Bursts: Crank the engine for approximately 10 seconds using the jumper wire. Then, wait for 20 seconds to allow the starter motor to cool and for the lacquer thinner to work. Repeat this cranking and resting cycle about 10 times. You should observe lacquer thinner being pumped out of the oil filter housing and into your drain pan.
-
Drain Remaining Lacquer Thinner: After cranking, remove the oil drain plug again and drain the remaining lacquer thinner from the oil pan. Observe the drained fluid; you may notice lumps of varnish or crud being expelled.
-
Flush with New Oil (Optional): Add a small amount of fresh engine oil through the normal oil fill point to help flush out any residual lacquer thinner from the oil pan. Drain this small amount of oil as well. Replace the oil drain plug securely.
-
Refill with New Engine Oil: Fill the engine crankcase with the correct amount of new engine oil as specified for your vehicle.
-
Prime Oil System: Before starting the engine, use the starter jumper wire again to crank the engine until fresh oil starts to flow out of the oil filter housing. This primes the oil system and ensures lubrication before engine start-up.
-
Install New Oil Filter: Install a new oil filter, tightening it to the manufacturer’s specification.
-
Top Off Oil: Check the engine oil level using the dipstick and top off as needed to reach the correct fill level.
-
Reinstall Starter Relay: Put the starter relay back into its original position in the fuse box and replace the fuse box cover.
-
Start Engine and Monitor: Start your engine using the ignition key. Monitor for any unusual noises or leaks.
Important Safety Precautions
- Flammability: Lacquer thinner is highly flammable. No smoking, open flames, or sparks should be present during this procedure. Work in a well-ventilated area to avoid inhaling fumes.
- Eye and Skin Protection: Wear safety glasses and chemical-resistant gloves to prevent lacquer thinner from contacting your eyes and skin.
- Engine Cranking without Lubrication: Be aware that you are cranking the engine with the starter motor without normal oil pressure lubrication during the flush process. While the short bursts of cranking are designed to minimize wear, prolonged or excessive cranking is not recommended. This DIY solution is presented as an alternative to more invasive repairs, based on a “nothing to lose” approach in specific situations where solenoid clogging is suspected.
- Vehicle Specifics: While this method was successfully used on a 2014 GMC Sierra 4WD, vehicle designs vary. Consult your vehicle’s repair manual or a trusted mechanic if you are unsure about any step or potential compatibility with your vehicle.
Success and Long-Term Results
In the original case with the GMC Sierra, the engine light reportedly went out within approximately 50 miles of driving after this lacquer thinner flush. Oil pressure behavior normalized, and the vehicle regained its ability to switch into V4 mode (cylinder deactivation). As a preventative measure, adding a half can of Sea Foam to the engine oil at each oil change was also mentioned as a follow-up step to help maintain system cleanliness. Since performing this flush, the vehicle reportedly drove over 500 miles without a recurrence of the P06DD code or oil pressure issues.
Conclusion
For owners of vehicles experiencing the OBD2 code P06DD, particularly when suspecting a stuck or clogged oil pump solenoid, this DIY lacquer thinner flush offers a potentially effective and budget-friendly alternative to extensive and costly repairs. While it’s essential to follow the steps carefully and prioritize safety, this method can save significant money and time. If the P06DD code persists after attempting this solution, further professional diagnosis and repair may be necessary. However, for many, this DIY approach may provide a successful resolution to this common oil pressure control system issue.
