P0232 – Fuel pump relay -circuit high

By Reinier (Contact Me)
Last Updated 2023-06-26
Automobile Repair Shop Owner

Table of Contents

1. What Does Code P0232 Mean?
2. Where is the P0232 sensor located?
3. What are the common causes of code P0232 ?
4. What are the symptoms of code P0232 ?
5. Get Help with P0232

What Does Code P0232 Mean?

OBD II fault code P0323 is a generic trouble code that is defined as, P0232 – “Fuel pump relay -circuit high”, or sometimes as P0232 – “Fuel pump relay –secondary circuit high”, and is set when the PCM (Powertrain Control Module) detects an abnormal current or voltage in one or more electrical circuits between the fuel pump and the relay that supplies the fuel pump with power.

Although there are meaningful differences between modern gasoline fuel injection systems in terms of capacities, fuel flow rates, and injection pressures, all fuel injection systems have one aspect in common, this aspect being fuel pumps that draw large amounts of current to operate.

In fact, many modern fuel pumps, and especially fuel pumps on Direct Injection systems routinely draw considerably more than 10 Amps, which places these pumps among the heaviest electrical consumers in many modern vehicles. Nonetheless, while supplying currents of 10 Amps and more to fuel pumps and other components do not present the electrical systems of modern vehicles with undue difficulties, the problem with such heavy currents is that they require heavy-gauge wiring and heavy-duty switchgear to prevent damage to the electrical system.

One way to conduct heavy currents effectively and efficiently is to use components called relays that act as heavy-duty switches when they are activated, but note that relays come in two “flavors”- electromechanical relays, and solid-state relays that do not include any moving parts. While both types of relays perform the same function, which is to “relay” direct battery power to components such as fuel pumps, the operating principles of solid-state relays are extremely technical and as such, the inner workings f the relays fall outside the scope of this article.

By way of contrast, electromechanical relays are simple devices that use a low-intensity current to energize an electromagnet to close two contact points. Consider the schematic diagram below-

In the case of fuel pump relays, the low-intensity current is typically supplied by the PCM when the ignition is turned on. In the schematic shown here, this current s represented by the white lines on the extreme left that connect the coil, which is the electromagnet. Going from left to right, the next circuit is the high-intensity circuit from the battery, but since the electromagnet is not energized, this circuit is open, and no current flows to the fuel pump.

Still going from left to right, the next circuit is the low-intensity circuit supplied by the PCM; this circuit is rendered in red to show that it is energized and the electromagnet is now activated and its contact points are closed. The last circuit is the high-intensity circuit that connects the fuel pump directly to the battery, and for as long as the low-intensity circuit remains energized, battery power will flow directly from the battery to the fuel pump via the high-intensity circuit. Thus, if power is removed from the low-intensity circuit for whatever reason, the magnetic field in the electromagnet will collapse, thereby causing the contact points to open, which will interrupt the power supply to the fuel pump.

However, the PCM monitors all the circuits that are implicated in supplying the fuel pump with power continuously for diagnostic purposes. These circuits include the low-intensity circuit, the high-intensity circuit from the battery to the fuel pump, and the driver circuit(s) in the PCM that vary the power supply to the fuel pump on returnless fuel systems. In short, returnless fuel systems vary the speed of the fuel pump to adapt the fuel pressure and flow to suit engine operating conditions, as opposed to the fuel pump delivering a constant pressure and flow rate, with excess fuel returning to the fuel tank via a dedicated fuel return line.

For a modern fuel injection system to work as expected, all the currents and voltages in the fuel pump’s power supply circuits must be within an acceptable range, so when the PCM detects an abnormally high voltage or current in the system, it will recognize that it cannot control the fuel pressure and rate of flow effectively. When this happens, the PCM will set one or more trouble codes, including P0232, and depending on both the application and the nature of the problem may also illuminate a warning light.

Where is the P0232 sensor located?

This image shows the location (circled) of the fuel pump relay in the fuse box of a 2004 Toyota Camry.

Note, however, that this location is not representative of the location of fuel pump relays on all vehicles. In most cases, the fuel pump relay may be located in the fuse box in the engine compartment, but in others, the fuel pump relay may be located in a fuse box under the dashboard, or outside of a fuse box in the engine compartment. Therefore, to avoid confusion and misdiagnoses, we strongly recommend that you research and identify the exact location of the fuel pump relay on the affected vehicle because fuel pump relays are often identical in shape and form to multiple other relays in fuse boxes.

What are the common causes of code P0232 ?

Common causes of code P0232 could include one or more of the following-

• Damaged, burnt, shorted, or corroded wiring and/or electrical connectors anywhere in the fuel pump’s control circuits
• Damaged or defective fuel pump relay
• The use of a substandard aftermarket fuel pump relay
• Clogged or dirty fuel filter
• Clogged or dirty fuel pickup sock/strainer in the fuel tank
• Pinched or restricted fuel line(s)
• Defective fuel pressure regulator
• Damaged, worn, or defective fuel pump
• Failed or failing PCM but note that since this is a rare event, the fault must be sought elsewhere before any control module is reprogrammed or replaced

What are the symptoms of code P0232 ?

Depending on the nature of the problem, some common symptoms of code P0232 could include one or more of the following-

• Stored trouble code and possibly an illuminated warning light
• In some cases, multiple additional codes may be present along with P0232, with fuel pressure-related codes being common
• The engine may stall or shut off unexpectedly or repeatedly at all engine speeds
• Fuel pump failure could occur if the fuel filter is clogged or dirty
• A no-start condition may be present
• A no-crank condition may be present
• The fuel pump may emit mechanical noises such as whining or grinding sounds
• The vehicle may be immobilized until the fault is found and corrected

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