What Is the P0042 Code?
Symptoms
Causes
Seriousness
Can I Still Drive?
Diagnose
Difficulty of Inspecting
Get Additional Help
The P0042 code definition is “HO2S Heater Control Circuit Bank 1 Sensor 3.” You’ll see this error code when your vehicle’s powertrain control module (PCM) or engine control module (ECM), also called your engine control unit (ECU), detects an issue with your vehicle’s heated O2 sensor’s heater control circuit for bank 1 sensor 3, which is the third sensor downstream from the engine in bank 1. As a generic powertrain code, you can find the P0042 code in many OBD-II-equipped vehicles.
More About the P0042 Code
Heated oxygen sensors in the exhaust system both before and after the catalytic converter help your PCM or ECM determine engine oxygen content. By monitoring both before and after the catalytic converter, the sensors are able to send information that allows your fuel system to monitor the catalytic converter efficiency and tweak your air/fuel ratio. All oxygen sensors must reach a certain temperature before they can start monitoring oxygen content, but in modern vehicles, to ensure higher efficiency, a heating element was added to reduce the time necessary to start operating. This code indicates that the circuit for one of these sensors has malfunctioned in some way.
Who Has the Lowest Price?
Some service centers will give you an online estimate to compare. Why drive around Town!?
What Are the Symptoms of a P0042 Code?
The most common symptom of the P0042 code is simply that the check engine light or other malfunction indicator lamp will turn on. In general, you won’t see many other symptoms if this is the only code you see in your vehicle. However, if this code is connected to any other diagnostic trouble codes, you could see any number of symptoms for those codes. Always look for information about other codes that turned up on your scan tool, including other O2 sensor codes as well as general engine codes, to see what symptoms you might be experiencing in your vehicle.
What Are Some Causes of a P0042 Code?
There are multiple possible triggers for the P0042 code, but the primary cause usually has to do with either a faulty oxygen sensor or a general problem with the oxygen sensor heater control circuit. For example, the heater circuit may have shorts, the heater wire may be corroded, or there may be concerns about corrosion of the oxygen sensor control circuit. In very rare cases, this may be due to a faulty PCM, but this is uncommon and should not be your first thought.
How Serious Is the P0042 Code?
The P0042 code will probably not result in any severe drivability problems right now, but that’s no reason to assume that you can ignore it. Over time, the P0042 code can cause reduced engine performance, as issues with the heated oxygen sensor control circuit can make it more difficult for your PCM or ECM to adjust the air/fuel ratio to its most optimal point accurately. Don’t ignore this code — manage it as soon as possible to reduce the likelihood that it will end up creating a larger problem down the line.
Can I Still Drive with a P0042 Code?
Physically, you’ll likely be able to continue to drive with the P0042 code active. However, this doesn’t mean that you should just keep driving. The P0042 code may not be an especially severe code, nor one that results in especially significant drivability concerns, but all codes that turn on your check engine light should be treated as serious in some way. The earlier you can fix the core problem, the more likely that it can be a simple and easy fix, rather than one that’s more difficult and costs potentially thousands of dollars.
How Easy Is It to Diagnose a P0042 Code?
Diagnosing a P0042 code isn’t always easy. While the code itself is fairly simple, figuring out the core problem can require you to read your scan tool, find a vehicle-specific repair manual, read technical service bulletins, and otherwise delve pretty far into your own understanding of the engine and the possible problems you could be experiencing. If you’re a DIYer and not especially confident doing it yourself, it’s best to talk to a professional instead.
How Difficult Is It to Inspect a P0042 Code?
As with diagnosis, inspection is also sometimes difficult for smaller components in your engine. You may, for example, need to perform a visual inspection, check wiring diagrams, and look at components of your vehicle impacted by other fault codes you see in your scan tool. This can be especially difficult if you’re not used to the inspection process for the oxygen sensor heater circuit and surrounding areas. If this isn’t an area you have a lot of experience with, chances are you’ll want to talk to an experienced mechanic instead of trying to do it yourself.
Need Additional Help with Your P0042 Code?
Many people end up requesting professional help with the P0042 code, which can be especially helpful if you don’t do a lot of DIY work on your own vehicle. The good news is that this is a fairly straightforward code, especially if it’s showing up by itself, so it shouldn’t be too much of a hassle to fix.
First, you’ll want to find an auto repair shop in your area. Although this code doesn’t usually come with drivability concerns that could require you to limit the amount of driving you do, finding a local auto repair shop is still important, as it makes it less of a hassle to take your vehicle in.
It’s also a good idea to check out the OBD-II database at KBB.com, especially if you’re seeing other codes alongside this one. The database will give you more insight into what repairs you could be looking at, allowing you to prepare yourself to visit the auto repair shop.
P0042 Q&A
Common Error Codes
Browse All OBD-II Codes
Get Recall Alerts
All recalls are considered serious. Stay safe. Take care of any recalls ASAP. The good news? Recall repairs are free when performed at a local dealer.