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P0304 Error in 1999 Honda CR-V: Causes, Fixes, and Valve Adjustment Advice

Model: 1999 Honda CR-V Fault Code: P0304 Posted: 2007-01-18 19:44

The check engine light is on and the vehicle has triggered error code P0304. I've already replaced the spark plugs, ignition wires, distributor cap, rotor, and fuel filter. After driving a short distance, the check engine light returns. The car is scheduled for a valve adjustment at a Honda dealership tomorrow, followed by a fuel injector inspection. As a non-technical owner, I'm trying to do everything possible to resolve this issue. The vehicle is due for inspection and will not pass with the check engine light on. Are there any other potential causes or troubleshooting steps that could help eliminate the P0304 code? Any advice would be greatly appreciated. Thanks, D

Related fault codes

P0304

Comments (3)

Anonymous 2007-01-29 03:50

I experienced exactly the same issue with both my 1999 and 1998 Honda CR-V. Over time, a valve can become stuck or tighten up, causing a misfire that the ECU detects as a P0304 code. Unfortunately, I let it go too long — when the engine started misfiring severely, one of my exhaust valves had burned out. At that point, the MIL (Malfunction Indicator Lamp) was blinking. On my first CR-V, this damage also ruined the catalytic converter. This valve problem has occurred twice on both vehicles. I recently spent a weekend disassembling and performing a full valve job. It's not an uncommon issue with older Honda CR-Vs, especially when not serviced regularly. Having a certified Honda technician perform a valve adjustment is likely the best course of action. I also replaced all spark components — plugs, wires, cap, rotor — as you did. This is a known but under-discussed problem in CR-V owners. Don't ignore it if the check engine light comes on. Best of luck! Steve

Anonymous 2007-01-29 09:49

Carbon buildup is a common and significant issue in older Honda engines, especially in models from the 1990s to early 2000s. It can contribute to misfires and trigger P0304 codes even after spark plug and ignition component replacements.

Anonymous 2008-04-04 12:32

If you own a 1997–2001 Honda CR-V, be aware of two known issues: First, the factory service manual does not recommend valve adjustments every 30,000 miles — despite earlier model years stating this requirement. This appears to be a marketing decision. Second, there is evidence of a manufacturing defect in some units where valve seats are not properly hardened, leading to premature wear and misfires. Once the check engine light comes on with P0304, you may face either a full valve job or even a cylinder head replacement. I wish I had known this sooner — I would have sold my 2001 CR-V years ago! This is why early-model CR-Vs are considered high-risk for engine-related issues. — Informed too late