Fuel Pressure

P0088 P0089 P0093 P1272 P1273 P1274

Fuel pressure problems.

Any of these codes will generally be triggered due to low or high fuel pressure or abnormal fuel pressure pulses detected by the fuel pressure sensor. The ecm judges fuel amount passing through to the fuel rail by comparing SCV (Suction Control Valve) pulse to actual rail pressure as measured by the rail pressure sensor. With these calculations the ecm can determine if fuel delivery is out of range with the comparison of expected vs actual.

Possible Causes

Some causes of these codes to be triggered are: low/high fuel pressure, SCV, fuel pump, air ingress into fuel system, fuel pressure sensor, fuel pressure relief valve, wiring. If you have an aftermarket performance chip installed on the vehicle, please remove it and see if the code will clear.

Common causes are the SCV and the fuel pressure relief valve. These can cause low fuel pressure and stalling.

The fuel pressure relief valve, will open if fuel pressure becomes too high. This can happen if the scv is failing and also if an aftermarket performance chip is installed on the car. It will be a high pressure condition followed by a low pressure condition when the relief valve opens.

Possible Solutions

The relief valve is located on the end of the fuel rail toward the rear of the engine. (see image left) To test the relief valve, remove the relief hose (as indicated), place another hose onto the relief valve and direct it into a container. Start the engine and rev it over 4,000rpm for at least 5 seconds. If no fuel comes out, the relief valve is still serviceable. If fuel does come out, it needs to be replaced. It is not advisable to blank the relief as it acts as a fail safe for over pressure incidents which in turn protects injectors etc from becoming over pressurised.

If the relief checks out ok, the problem is most likely the SCV. The SCV is located on the back of the fuel pump. It is simple to remove, 1 electrical plug and 2 Allen key bolts. Be sure to remove the old gasket and o ring.

The SCV can be tested. If terminals 1 and 2 are probed with a multimeter, it should show 1.8-2.4 ohms. This test will tell you if the solenoid is ok, but does not tell you the condition of the pintle. (see image right)

It is best to replace the SCV with either a genuine Nissan or a genuine Denso. Denso is the O.E manufacturer.

A cause for air ingress into the fuel system is things like cracked or not securely clamped fuel hoses, aftermarket fuel filters, poorly fit water sensor. This type of symptom will generally only be noticeable after the vehicle has been parked overnight.

The fuel pressure sensor uses the 5v circuit to deliver a signal to the ecm regarding fuel pressure. It is not very common for this item to fail. If it did, it would need to be probed, and checked for power, ground and signal feed. If codes P0652 or P0653 were triggered along with the fuel pump codes, they would need to be dealt with first as they are indicative of an open or short to ground in the 5v circuit.

DENSO Suction Control Valves