TechShop’s The Code Reader Podcast

Today we’ll be looking at DTC P2422, which indicates that the evaporative emissions canister vent valve is obstructed. The particular vehicle we were working on was a 2008 Honda Accord, and a Honda technical service bulletin, or TSB was a big help to point us in the right direction with solving this code.

One of our long-time company writers Gary Goms told had been called to a local shop to lend his expertise and tools on a 2012 Chevy Impala with the flex-fuel, 3.6L GDI, or gasoline direct injection engine. There was an intermittent loss of power complaint that the shop couldn’t figure out.

This TSB was released by General Motors, covering most of their large SUV’s and vans that have been produced from 2002 and up. The related DTCs that a technician may find are P0420, Catalyst Efficiency Below Threshold, and/or P0430, which is the same thing, Catalyst Efficiency Below Threshold, just for bank 2. Technicians are seeing these codes on low mileage vehicles, or vehicles that have recently had the catalytic converter replaced.

The complete symptom is a cold-start misfire or a rough idle concern. Upon inspection, the technician will find medium to high misfire counts and the symptom always occurs on one or two cylinders and goes away when the engine warms up. Now, a misfire or rough idle isn’t that uncommon in the grand scheme of things, but in this case it’s what’s causing them that’s unusual.

I was looking through some TSB’s and realized when we did the original P0172 podcast, I completely forgot about one possible cause of the problem that has actually been fairly common for a long time. And in reality, it’s so simple and so basic, that it could be easy to overlook. Excess fuel in the engine oil causes DTC P0172 to set, and the solution is an oil and filter change.

An ASE-certified technician walks listeners through a diagnostic dilemma with 11 trouble codes, an intermittent problem and a dash board lit up like a Christmas tree on a 2001 Blazer.

This is another problem that arrived at the shop of our TechShop contributor, Olle Gladso and the car was a 2013 Volkswagen Jetta with a two-liter TDI engine. It had an intermittent problem. Sometimes it ran great, but sometimes it would idle high and when you would press on the accelerator, nothing would happen.

A customer brought in a 2007 Subaru Legacy with the 2.5L 4-cylinder EJ25 engine. The owner complained of an engine vibration. From the initial description, it sounded like a pretty typical misfire issue. It turns out that about six months prior, the customer had the vehicle at another shop and the engine was overhauled. It was immediately after that the problem began. 

A customer brought in a 2004 BMW X5 with the well-known M54 engine. The complaint was that the engine was running unusually rough and the check engine light was on. A DTC scan revealed DTC P0304, cylinder misfire cylinder 4.

A customer brought in a 2003 Mitsubishi Eclipse with the 4G64 2.4 liter and a complaint of a rough running condition and a no-start when warm. A DTC scan revealed DTC P0340, or CMP (camshaft position sensor) Circuit Malfunction Bank 1.

This code monitors the oxygen sensor voltage and when it sets, it means that the PCM sees that it has remained low for over a predetermined amount of time, usually 2-4 minutes, but that varies depending on manufacturer.

TechShop discusses the relationship between clearing DTCs and readiness monitors.

An ASE Certified Technician breaks down DTC P0300, identifies the symptoms and causes and walks listeners through a diagnostic solution.

TechShop's ASE-certified technicians share and review a Technical Service Bulletin that applies to 2016 to 2019 Ford Fiesta vehicles with DTC P0128.

An ASE Certified technician walks listeners through an unusual problem on a 2005 GMC Sierra 2500 4WD truck. This tip is brought to you by AllData.

When P0172 is stored, it means that the control unit has recognized through the readings from the oxygen or air/fuel ratio sensors that there is a lack of oxygen in the exhaust, representing too much fuel in the combustion process.

P0455 is a common EVAP trouble code and one whose description quite often accurately reflects what is causing the problem. The purpose of the evaporative emission system is to prevent the fuel vapors in the gas tank from escaping into the atmosphere and when this code sets, it’s a good bet that they are.

An ASE Certified Technician breaks down DTC P0171, identifies the symptoms and causes and walks listeners through a diagnostic solution.

Our scan tool is reading a diagnostic trouble code of P0401- EGR Insufficient Flow. An ASE Certified Technician identifies the symptoms and causes of a P0401, and walks listeners through a diagnostic solution.

An ASE Certified Technician identifies the symptoms and causes of a P0420, walks listeners through a diagnostic solution.

An ASE Certified Technician identifies the symptoms and causes of a P0128 walks listeners through a diagnostic solution.