NHTSA ID Number: 11028516
Manufacturer Communication Number: A26-002
TSB/Document Date: 2026-02-06
Summary
Service Bulletin - The piston ring function deteriorates due to ring low wear toughness and sticking from sludge. Oil adheres to the spark plug leading to carbon fouling and misfire. This can set DTCs P0301 No. 1 cylinder misfire detected, P0302 No. 2 cylinder misfire detected, P0303 No. 3 cylinder misfire detected, P0304 No. 4 cylinder misfire detected, and cause the MIL to come on.
If the PDF is very large, it may not load in the preview below.
Some older TSBs had multiple PDFs — visit the NHTSA Website to view all PDFs.
If the TSB PDF does not show, download or view it on the NHTSA Website.
Click on the (+) Plus Sign
Then Click on Associated Document(s)
- Advanced protection against the four main causes of engine...
- Delivers 40% stronger wear protection than industry...
- Provides 15% better deposit defense vs. industry standards...
- Up to 2.5X better heat protection vs. industry standards to...
- Engineered for excellent low-temperature flow, reducing...
- Formulated for engines with 75,000 miles or more, Valvoline...
- Delivers 20% better wear protection and 15% better sludge...
- Extra detergents safeguard against friction, corrosion and...
- Advanced friction-fighting additives help maximize...
- Provides performance benefits for high mileage, new and...
Search NHTSA Database for Recalls
Search NHTSA Database for Vehicle Investigations
View Latest Vehicle Investigations
Search NHTSA Database for Vehicle Complaints
View Latest Vehicle Complaints
TSB/Document ID: A26-002
Replacement Service Bulletin Number:
MFR Communication Date: 2026-02-01
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: ENGINE
MFR Component System:
MFR Component Subsystem:
Previous TSB | Next TSB |
Gasket Remover/Pan Separator
Piston Ring Expander
Piston Ring Compressor
NOTE: Each dealer was sent one cylinder wall inspection tool.
Repair Procedure B
Tool Name
Lif t table
Cylinder Wall Inspection Tool
NOTE: Each dealer was sent one cylinder wall inspection tool.
Page 8 of 109
INSPECTION PROCEDURE
1.
Connect the i-HDS and check for the following DTCs:
•
•
•
•
P0301
P0302
P0303
P0304
- No.
- No.
- No.
- No.
1 Cylinder
2 Cylinder
3 Cylinder
4 Cylinder
Misf ire Detected
Misf ire Detected
Misf ire Detected
Misf ire Detected
Are any of these DTCs stored?
YES – Go to step 2.
NO – Stop. This bulletin does not apply. Continue with normal troubleshooting.
2.
Relieve the fuel pressure using i-HDS. Refer to the service manual for the full procedure.
3.
Remove the engine cover, then remove the appropriate Ignition coils and spark plugs based on the DTCs stored.
Example: If P0301 is stored, remove the ignition coil on cylinder No. 1.
Page 9 of 109
4.
Check the spark plug(s) of the affected cylinder(s).
Example: If P0301 is stored, check the spark plug on cylinder No. 1.
DTC Stored
P0301
Diagnostic
Remove the #1 cylinder spark plug
and inspect for fouling.
Spark plug
condition?
Repair Process
Not fouled
This bulletin does not apply. Continue with
normal troubleshooting.
Fouled
Not fouled
P0302
Remove the #2 cylinder spark plug
and inspect for fouling.
Fouled
Not fouled
P0303
Remove the #3 cylinder spark plug
and inspect for fouling.
Fouled
P0304
Remove the #4 cylinder spark plug
and inspect for fouling.
Not fouled
Fouled
P0305
P0306
Proceed to step 5.
This bulletin does not apply. Continue with
normal troubleshooting.
Proceed to step 5.
This bulletin does not apply. Continue with
normal troubleshooting.
Proceed to step 5.
This bulletin does not apply. Continue with
normal troubleshooting.
Proceed to step 5.
This bulletin does not apply. Continue with
normal troubleshooting.
Page 10 of 109
5.
Remove the af f ected cylinder head(s) to inspect the cylinder bores.
DTCs Stored with fouled
spark plug(s)
P0301, P0302, or P0303
P0304
Diagnostic
Remove the rear cylinder head and inspect cylinder bores 1-3 for scratching or
scoring using the cylinder head inspection tool.
Remove the front and rear cylinder heads and inspect cylinder bores 1-4 for
scratching or scoring using the cylinder head inspection tool.
NOTICE
•
•
•
Use fender covers to avoid damaging painted surfaces.
To avoid damaging any wires and terminals, unplug the circuit connectors carefully while holding the connector
portion.
Mark all the circuits and hoses to avoid misconnection. Make sure they do not contact other circuit wiring, hoses,
or interfere with other parts.
1.
Remove both front wheels to allow the vehicle to be fully lowered.
2.
Do the 12-volt battery removal procedure.
3.
Disconnect the fuel feed hose quick-connect fitting at the bulkhead.
Page 11 of 109
4.
Remove the radiator cap.
5.
Raise the vehicle.
6.
Remove the front splash shield.
7.
8.
Loosen the drain plug on the radiator and drain the coolant.
Page 12 of 109
9.
Drain the remaining coolant from the engine by installing a 5/16 in. inner diameter rubber hose (commercially
available) onto the block drain bolt located at the rear of the engine block, then loosen the drain bolt. Then
disconnect the oil pressure switch connector.
10. Remove the subframe stif f ener.
Page 13 of 109
11. Remove exhaust pipe A.
12. Depending on the diagnosis, remove either the rear or both of the WU-TWC support bracket bolts.
Page 14 of 109
13. Remove the EGR pipe lower mounting nuts (A).
14. Remove the left front fender liner.
15. Lower the vehicle.
16. Disconnect the breather pipe (A), then remove the intake air duct (B).
Page 15 of 109
17. Disconnect the PCV hose (A), the brake booster vacuum hose (B), and the IMT actuator connector (C).
18. Disconnect the EVAP canister hose (A), the EVAP canister purge valve connector (B), the throttle actuator
connector (C), and the MAP sensor connector (D). Then disconnect and plug the water bypass hoses (E).
19. Remove the alternator.
Page 16 of 109
20. Remove the engine intake upper cover (A).
FOR INSTALLATION:
1.
Install the upper cover (A) with a new gasket. Tighten the bolts and nuts to 12 N·m (8.9 lb-ft) in three steps in
the sequence shown below.
Page 17 of 109
21. Remove the intake manifold bolts and nuts in three steps, then remove the intake manifold with the throttle body
attached.
FOR INSTALLATION:
1.
Install the intake manifold with a new gasket. Tighten the bolts and nuts to 22 N·m (16 lb-ft) in three steps in
the sequence shown below.
Page 18 of 109
22. Lift the power steering reservoir (A) from the clamp, then remove the drive belt.
23. Remove the drive belt auto-tensioner.
24. Remove the bolt (B) securing the power steering hose bracket (C), then remove the bolts for the power steering
pump (A) and secure the power steering pump out of the way.
NOTE: Do not remove any of the power steering hoses.
25. Remove the cylinder head cover on the affected cylinder bank(s).
26. Remove the engine harness holder bolt on the side engine mount.
27. Set the number 1 cylinder to TDC.
Page 19 of 109
28. Remove the PCM cover (A).
29. Remove the harness clamps (A), then disconnect the PCM connectors (B), and the engine wire harness
connector (C), then remove the PCM with the bracket.
Page 20 of 109
30. Remove the ground cable bracket (A), then remove the upper half of the side engine mount bracket (B).
31. Remove the front upper timing cover (A) and the rear upper timing cover (B).
32. Raise the vehicle.
Page 21 of 109
33. Remove the crankshaft pulley.
34. Remove the lower timing cover.
35. Lower the vehicle.
36. Remove the lower half of the side engine mount bracket.
Page 22 of 109
37. Remove the timing belt auto-tensioner.
NOTE: See the service manual for the procedure to compress the tensioner for installation.
38. Remove the timing belt.
39. Depending on the diagnosis, remove some or all of the following:
•
ECT sensor 1 connector
•
Front rocker arm oil pressure switch connector
•
Rear rocker arm oil pressure switch connector
•
CMP sensor connector
•
Front A/F sensor 1 connector
•
Rear A/F sensor 1 connector
•
Front secondary HO2S connector
•
Rear secondary HO2S connector
•
Rocker arm oil control solenoid A connector (bank one)
•
Rocker arm oil control solenoid A connector (bank two)
•
Rocker arm oil control solenoid B connector (bank one)
•
Knock sensor connector
Page 23 of 109
40. Remove the quick-connect fitting cover (A), then disconnect the fuel feed hose (B).
41. Remove the EVAP canister purge joint with the bracket.
42. Remove the fuel rail connecting joint hose.
Page 24 of 109
43. Remove the EGR pipe upper mounting bolts (A), then remove the EGR pipe.
NOTE: Use new gaskets on installation.
44. Remove the upper radiator hose (A) and the lower radiator hose (B).
Page 25 of 109
45. Separate the water passage from the cylinder heads, then remove the water passage assembly.
46. Remove the starter by removing the harness clamp (A), then disconnect the positive starter cable (B) and the S
terminal connector (C) from the starter. Remove the lower radiator hose bracket (D) and the dipstick (E), then
remove the starter assembly (F).
NOTE: Install with a new gasket (G).
Page 26 of 109
47. Unbolt the appropriate WU-TWC(s) from the cylinder head(s) based on the diagnosis.
NOTE: The WU-TWC can be set aside. Cover the opening with shop towels to prevent coolant from entering.
48. Remove the appropriate cylinder head(s) with the injector base attached.
NOTE:
• Depending on diagnosis, you will remove the rear bank cylinder head or both cylinder heads.
• To prevent warpage, loosen the bolts in sequence, 1/3 turn at a time, repeat until all the bolts are loosened.
Page 27 of 109
49. Measure the head bolts to determine if they need replacement. If either diameter is less than 11.3 mm (0.445 in.),
replace the cylinder head bolt.
50. Use the cylinder wall inspection tool to inspect the cylinder walls for vertical scratching.
NOTE:
•
•
For inf ormation on using the cylinder wall inspection tool, ref er to the Job Aid “Cylinder Wall Inspection Tool”
and/or Tech2Tech “Check out the Cylinder Wall Inspection Tool”.
Do not use a f ingernail or pencil lead to determine if an engine block is usable. Light to moderate scratches
that are detected with your f ingernail will pass the inspection when using the cylinder wall inspection tool.
Check Out the Cylinder Wall Inspection Tool
Cylinder Wall Inspection Tool (07AAJ-R70A301)
Page 28 of 109
51. Determine the repair direction based on the cylinder inspection:
DTCs Stored
Cylinder Bore
Condition?
Repair Direction
Do Repair Procedure A:
No scratching or
scoring detected
P0301, P0302,
or P0303
•
•
•
•
Clean pistons 1-3
Replace piston rings 1-3
Replace spark plugs 1-4
Update PCM software
Do Repair Procedure B:
Scratching or scoring
detected
•
Remove front cylinder head (follow the steps above to
remove the front cylinder head, then proceed to Repair
Procedure B)
•
Replace short block
•
Replace spark plugs 1-4
•
Update PCM software
Do Repair Procedure A:
No scratching or
scoring detected
P0304
•
•
•
Clean pistons 1-4
Replace piston rings 1-4
Replace spark plugs 1-4
•
Update PCM software
Do Repair Procedure B:
Scratching or scoring
detected
•
Replace short block
•
Replace spark plugs 1-4
•
Update PCM software
Page 29 of 109
REPAIR PROCEDURE A
Piston removal, Cleaning, and Ring Replacement
1.
Raise the vehicle.
2.
Remove the CKP sensor cover and bolts, then disconnect the CKP sensor connector.
3.
Remove the torque converter case cover and the four bolts securing the oil pan to the transmission.
Page 30 of 109
4.
Remove all bolts securing the oil pan.
5.
Using a flat blade screwdriver, separate the oil pan from the engine block in the areas shown.
Page 31 of 109
6.
Remove the oil strainer and baffle plate.
7.
Remove the appropriate piston(s) depending on diagnosis.
NOTICE
- CEL Doctor: The ANCEL AD310 is one of the best-selling OBD II scanners on the market and is recommended by Scotty Kilmer, a YouTuber and auto mechanic. It can easily determine the cause of the check engine light coming on. After repairing the vehicle's problems, it can quickly read and clear diagnostic trouble codes of emission system, read live data & hard memory data, view freeze frame, I/M monitor readiness and collect vehicle information.
- Sturdy and Compact: Equipped with a 2.5 foot cable made of very thick, flexible insulation. It is important to have a sturdy scanner as it can easily fall to the ground when working in a car. The AD310 OBD2 scanner is a well-constructed mechanic tool with a sleek design. It weighs 12 ounces and measures 8.9 x 6.9 x 1.4 inches. Thanks to its compact design and light weight, transporting the device is not a problem. The buttons are clearly labelled and the screen is large and displays results clearly.
- Accurate Fast and Easy to Use: The AD310 scanner can help you or your mechanic understand if your car is in good condition, provides exceptionally accurate and fast results, reads and clears engine trouble emission codes in seconds after you fixed the problem. This device will let you know immediately and fix the problem right away without any car knowledge. No need for batteries or a charger, get power directly from the OBDII Data Link Connector in your vehicle.
- OBDII Protocols and Car Compatibility: Many cheap scan tools do not really support all OBD2 protocols. AD310 scanner as it can support all OBDII protocols such as KWP2000, J1850 VPW, ISO9141, J1850 PWM and CAN. This device also has extensive vehicle compatibility with 1996 US-based, 2000 EU-based and Asian cars, light trucks, SUVs, as well as newer OBD2 and CAN vehicles both domestic and foreign. Pls confirm with our customer service whether it is compatible with your vehicle before purchasing.
- Home Necessity and Worthy to Own: This is an excellent code reader to travel or home with as it weighs less and it is compact in design. You can easily slide it in your backpack as you head to the garage, or put it on the dashboard, this will be a great fit for you. The AD310 is not only portable, but also accurate and fast in performance. Moreover, it covers various car brands and is suitable for people who just need a code reader to check their car.
- Multi-Functions - Practical Multi-Functions OBD2 code reader features built-in OBD2 DTC lookup library, which help you to determine the cause of the engine light, read code, erase code, view freeze frame, I/M ready, vehicle information, data flow, real-time curve, get vehicle speed information, calculate load value, engine coolant temperature, get engine speed.
- Wide Capability - Supports 9 protocols compatible with most 1996 US-Based, 2000 EU-Based and Asian cars, and newer OBD II & CAN domestic or import vehicles. Supports 6 languages - English,German, Dutch, Spanish, French, Italian.
- 2.8" LCD Display - Designed with a clear display 2.8" Large LCD screen - white backlight and contrast adjustment. No need any battery or charger, OBD reader gets the power directly from your vehicle through the OBDII Data Link Connector.
- Compact Design - Car diagnostic scanner is equipped with a 2.5 feet long cable and made of a very thick flexible insulator.There are 6 buttons on OBD2 Scanner:scroll up/down,enter/exit and buttons that quick query VIN vehicle number& the DTC fault code.
- ABS / Airbag codes NOT Supported - It is able to read and clear check engine information which is part of OBDII system, but it cannot work with non-OBDII systems, including ABS / Airbag / Oil Service Light, etc.
- 【Your Personal CEL Doctor – Read & Clear Engine Codes】The NT301 OBD2 scanner lets you read diagnostic trouble codes (DTCs), check em-issions readiness, turn off your Check Engine Light (CEL) or MIL, reset monitors, and view live data streams. It retrieves your vehicle's VIN instantly. Like all standard OBD2 scanners, it clears codes only after repairs are completed—if the issue persists, the code will return. Designed for DIYers who want to understand what’s really going on under the hood.
- 【Easy Code Reading – Just Plug & Play】Simply plug into the OBD2 port, turn the ignition to “ON” (engine off), and select the correct menu: Select OBDII-> Wait for seconds-> Select Read codes. For accurate results, ensure your vehicle is compatible and the OBD2 port is free from damage or wiring issues. No batteries needed— powered directly by your car.
- 【Live Data Graphing & Accuracy for Most OBD2 Vehicles】View and log live sensor data in graph form—monitor oxygen sensors, fuel trims, coolant temp, RPM, and more. Spot trends and suspicious values in real time. Compatible with most 1996+ gasoline cars, light trucks, and SUVs sold in the U.S., as well as many 2000+ European and Asian models. Also works on 12V diesel vehicles equipped with OBD2.
- 【S-mog Check Helper – Know Your Readiness Status at a Glance】With dedicated I/M readiness hotkeys and a simple Red-Yellow-Green LED indicator, you’ll instantly know if your vehicle is ready for em-issions testing. Built-in speaker provides audio feedback. No guesswork—just confidence before you head to the test center.
- 【A Must-Have Tool for Every Home Mechanic】Compact, rugged, and ready to use right out of the box. The 2.8” color screen is easy to read, even in daylight. No charging or setup required—just plug into the 16-pin DLC and start diagnosing. Recommended by professional mechanics on YouTube and trusted by DIYers worldwide.
Last update on 2026-03-23 / Affiliate links / Images from Amazon Product Advertising API
This product presentation was made with AAWP plugin.