Workshop Manuals Factory service & repair Honda

Honda common faults and how to fix them

Faults that are well known on Honda models we hold manuals for: what the owner notices, what causes it, and the pages in our manuals that cover the repair.

Honda P0420: catalyst efficiency code on the Civic, Element, Fit, Odyssey and Insight

Symptoms

The check engine light comes on with P0420 (catalyst system efficiency below threshold). Usually the car drives normally, but on some older Civics the code comes with engine pinging under load and misfire codes P0301 to P0304.

Cause

Honda bulletins give different causes by model. On the 2003 Element, the engine computer misread sensor inputs under certain driving conditions. On the 2008 Fit, it misread idle conditions, upsetting fuel and ignition control. On the 1999 Odyssey, the catalytic converter itself deteriorated. On some 1990s Civics, the cause was poor connections at the distributor's igniter terminals. The 2000–2001 Insight had a campaign to replace the engine computer.

Fix

Check for exhaust leaks and misfires first, as both set P0420. Then follow the bulletin for the car. For the Element, the Honda P0420 fix is a software update. For the Fit, the bulletin replaces the catalytic converter and updates the software. On the Odyssey, a new converter is fitted; it is covered by the 8-year/80,000-mile US emissions warranty. On the Civic, Civic P0420 bulletin 05-027 re-crimps the distributor wires first, then replaces the converter if the code is stored.

Repair instructions on this site

Sources: Honda technical service bulletins 03-031, 10-015, 03-073 and 05-027; Honda campaign 07-038.

Honda P0171 and P0172: fuel system lean or rich codes

Symptoms

The check engine light comes on with P0171 (fuel system too lean) and sometimes P0172 (fuel system too rich). The car usually drives normally.

Cause

On the 1998–2000 Accord four-cylinder, Honda bulletin 00-018 gives the probable cause as moisture in the fuel pressure regulator. On the 2005 Accord Hybrid V6, bulletin 06-039 says the engine computer can wrongly calculate a lean condition on bank 1 when nothing is faulty, made more likely by 10 percent ethanol fuel, driving above 3,000 feet, hot weather and valve clearances at the loose end of the range. A Honda Service News tip for 2001–2004 Civic, CR-V, Element, Odyssey and 2003–2004 Accord advises checking the short-term fuel trim to find the cause of P0171.

Fix

Read the short-term and long-term fuel trims, and smoke-test for intake leaks before replacing parts. On a 1998–2000 Accord, the Honda P0172 bulletin covers the fuel pressure regulator. On the 2005 Accord Hybrid, the Honda P0171 bulletin explains the calculation error and the repair. For other models, follow the fuel trim tip before replacing sensors.

Repair instructions on this site

Sources: Honda technical service bulletins 00-018 and 06-039; Honda Service News, DTC P0171.

Honda power steering pump: whining, moaning or whistling

Symptoms

A moan or whine when turning the steering wheel, often only with the engine cold, sometimes with air bubbles or foam in the power steering reservoir. Others hear a whistle or a constant whine from the pump.

Cause

Honda bulletins give three causes. For the cold-start moan and foaming, bulletin 07-086 replaces the O-ring at the pump's inlet joint, where air can be drawn in. A loose crimp on the high-pressure hose causes a whine or whistle on the 2003 Accord V6 and early 2002–2003 Civic coupes. On the 1999–2003 Odyssey and 2003 Pilot, a clogged screen in the power steering reservoir makes the pump whine.

Fix

Check the fluid level and look for foam first. For a cold-start moan, the Honda power steering pump bulletin replaces the O-ring on the inlet joint and refills with Honda power steering fluid. For a whistle, check the crimp on the high-pressure hose as the Accord power steering tip describes. On an Odyssey or Pilot, replace the reservoir, as the Odyssey power steering pump tip advises, before condemning the pump.

Repair instructions on this site

Sources: Honda technical service bulletin 07-086; Honda Service News, April 2003.